Doing some C learnin'.

Also, reformatted all the problems.

.gitignore

@@ -1,3 +1,6 @@
+# ---> C
+a.out
+
 # ---> Go
 # Compiled Object files, Static and Dynamic libs (Shared Objects)
 *.o

2016/day01/day01.rs

@@ -0,0 +1,42 @@
+use std::fmt;
+mod helpers;
+
+enum Direction {
+    North,
+    East,
+    South,
+    West
+}
+
+
+struct Position {
+    x: i32,
+    y: i32,
+    dir: Direction,
+}
+
+impl fmt::Display for Position {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "({}, {}: {})", self.x, self.y, string_dir(self.dir))
+    }
+}
+
+fn string_dir(d: Direction) -> String {
+    match d {
+        Direction::North => String::from("North"),
+        Direction::East => String::from("East"),
+        Direction::South => String::from("South"),
+        Direction::West => String::from("West"),
+    }
+}
+
+fn main() {
+    let input = helpers::read_std_in();
+    let split = input.split(",");
+    for mut s in split {
+        s = s.trim();
+        println!("{}", s);
+    }
+    let p = Position{ x: 0, y: 0, dir: Direction::North };
+    println!("{}", p)
+}

2016/day01/helpers.rs

@@ -0,0 +1,20 @@
+use std::io;
+
+pub fn read_std_in() -> String {
+    let mut input = String::new();
+    let mut done = false;
+    while !done {
+        match io::stdin().read_line(&mut input) {
+            Ok(n) => {
+                if n == 0 {
+                    done = true;
+                }
+            },
+            Err(error) => {
+                println!("error: {}", error);
+                done = true;
+            },
+        }
+    }
+    input
+}

2016/day01/input2

@@ -0,0 +1,15 @@
+R3, L5, R2, L1, L2, R5, L2, R2, L2, L2, L1, R2,
+L2, R4, R4, R1, L2, L3, R3, L1, R2, L2, L4, R4,
+R5, L3, R3, L3, L3, R4, R5, L3, R3, L5, L1, L2,
+R2, L1, R3, R1, L1, R187, L1, R2, R47, L5, L1,
+L2, R4, R3, L3, R3, R4, R1, R3, L1, L4, L1, R2,
+L1, R4, R5, L1, R77, L5, L4, R3, L2, R4, R5, R5,
+L2, L2, R2, R5, L2, R194, R5, L2, R4, L5, L4,
+L2, R5, L3, L2, L5, R5, R2, L3, R3, R1, L4, R2,
+L1, R5, L1, R5, L1, L1, R3, L1, R5, R2, R5, R5,
+L4, L5, L5, L5, R3, L2, L5, L4, R3, R1, R1, R4,
+L2, L4, R5, R5, R4, L2, L2, R5, R5, L5, L2, R4,
+R4, L4, R1, L3, R1, L1, L1, L1, L4, R5, R4, L4,
+L4, R5, R3, L2, L2, R3, R1, R4, L3, R1, L4, R3,
+L3, L2, R2, R2, R2, L1, L4, R3, R2, R2, L3, R2,
+L3, L2, R4, L2, R3, L4, R5, R4, R1, R5, R3

2017/day01/day01.c

@@ -0,0 +1,68 @@
+#include <stdio.h>
+
+void part1() {
+  printf("Part 1\n");
+
+  int result = 0;
+  char first = 0, prev, ch;
+  ch = getchar();
+
+  while(ch) {
+    if(first == 0) { first = ch; }
+    prev = ch;
+    ch = getchar();
+    if(ch == '\n') {
+      break;
+    }
+    if(ch == prev) {
+      result += prev - '0';
+    }
+  }
+
+  if(prev == first) {
+    result += prev - '0';
+  }
+
+  printf("%d\n", result);
+}
+
+void part2() {
+  printf("Part 2\n");
+
+  int result = 0;
+  char first = 0, prev, ch;
+  ch = getchar();
+  char* input;
+  gets
+
+  while(ch) {
+    if(first == 0) { first = ch; }
+    prev = ch;
+    ch = getchar();
+    if(ch == '\n') {
+      break;
+    }
+    if(ch == prev) {
+      result += prev - '0';
+    }
+  }
+
+  if(prev == first) {
+    result += prev - '0';
+  }
+
+  printf("%d\n", result);
+}
+
+int main(int argc, char **argv) {
+  printf("Args: %d\n", argc);
+  int doPart = 1;
+  if(argc > 1) { doPart = argv[1][0] - '0'; }
+  if(doPart == 1) {
+    part1();
+  } else {
+    part2();
+  }
+  return 0;
+}
+

2017/day01/problem

@@ -2,54 +2,78 @@ Advent of Code
 
 --- Day 1: Inverse Captcha ---
 
-   The night before Christmas, one of Santa's Elves calls you in a panic. "The printer's broken! We can't print the Naughty or Nice List!" By the time you make it to sub-basement 17, there are only a few minutes until midnight. "We have
+   The night before Christmas, one of Santa's Elves calls you in a panic. "The
-   a big problem," she says; "there must be almost fifty bugs in this system, but nothing else can print The List. Stand in this square, quick! There's no time to explain; if you can convince them to pay you in stars, you'll be able
+   printer's broken! We can't print the Naughty or Nice List!" By the time you
-   to--" She pulls a lever and the world goes blurry.
+   make it to sub-basement 17, there are only a few minutes until midnight. "We
+   have a big problem," she says; "there must be almost fifty bugs in this
+   system, but nothing else can print The List. Stand in this square, quick!
+   There's no time to explain; if you can convince them to pay you in stars,
+   you'll be able to--" She pulls a lever and the world goes blurry.
 
-   When your eyes can focus again, everything seems a lot more pixelated than before. She must have sent you inside the computer! You check the system clock: 25 milliseconds until midnight. With that much time, you should be able to
+   When your eyes can focus again, everything seems a lot more pixelated than
-   collect all fifty stars by December 25th.
+   before. She must have sent you inside the computer! You check the system
+   clock: 25 milliseconds until midnight. With that much time, you should be
+   able to collect all fifty stars by December 25th.
 
-   Collect stars by solving puzzles. Two puzzles will be made available on each day millisecond in the advent calendar; the second puzzle is unlocked when you complete the first. Each puzzle grants one star. Good luck!
+   Collect stars by solving puzzles. Two puzzles will be made available on each
+   day millisecond in the advent calendar; the second puzzle is unlocked when
+   you complete the first. Each puzzle grants one star. Good luck!
 
-   You're standing in a room with "digitization quarantine" written in LEDs along one wall. The only door is locked, but it includes a small interface. "Restricted Area - Strictly No Digitized Users Allowed."
+   You're standing in a room with "digitization quarantine" written in LEDs
+   along one wall. The only door is locked, but it includes a small interface.
+   "Restricted Area - Strictly No Digitized Users Allowed."
 
-   It goes on to explain that you may only leave by solving a captcha to prove you're not a human. Apparently, you only get one millisecond to solve the captcha: too fast for a normal human, but it feels like hours to you.
+   It goes on to explain that you may only leave by solving a captcha to prove
+   you're not a human. Apparently, you only get one millisecond to solve the
+   captcha: too fast for a normal human, but it feels like hours to you.
 
-   The captcha requires you to review a sequence of digits (your puzzle input) and find the sum of all digits that match the next digit in the list. The list is circular, so the digit after the last digit is the first digit in the list.
+   The captcha requires you to review a sequence of digits (your puzzle input)
+   and find the sum of all digits that match the next digit in the list. The
+   list is circular, so the digit after the last digit is the first digit in
+   the list.
 
    For example:
 
-     • 1122 produces a sum of 3 (1 + 2) because the first digit (1) matches the second digit and the third digit (2) matches the fourth digit.
+     • 1122 produces a sum of 3 (1 + 2) because the first digit (1) matches the
-     • 1111 produces 4 because each digit (all 1) matches the next.
+       second digit and the third digit (2) matches the fourth digit.
+     • 1111 produces 4 because each digit (all 1) matches the next. 
      • 1234 produces 0 because no digit matches the next.
-     • 91212129 produces 9 because the only digit that matches the next one is the last digit, 9.
+     • 91212129 produces 9 because the only digit that matches the next one is 
+       the last digit, 9.
 
    What is the solution to your captcha?
 
-   Your puzzle answer was ____.
+   Your puzzle answer was 1144.
 
 --- Part Two ---
 
-   You notice a progress bar that jumps to 50% completion. Apparently, the door isn't yet satisfied, but it did emit a star as encouragement. The instructions change:
+   You notice a progress bar that jumps to 50% completion. Apparently, the door
+   isn't yet satisfied, but it did emit a star as encouragement. The
+   instructions change:
 
-   Now, instead of considering the next digit, it wants you to consider the digit halfway around the circular list. That is, if your list contains 10 items, only include a digit in your sum if the digit 10/2 = 5 steps forward matches
+   Now, instead of considering the next digit, it wants you to consider the
-   it. Fortunately, your list has an even number of elements.
+   digit halfway around the circular list. That is, if your list contains 10
+   items, only include a digit in your sum if the digit 10/2 = 5 steps forward
+   matches it. Fortunately, your list has an even number of elements.
 
    For example:
 
-     • 1212 produces 6: the list contains 4 items, and all four digits match the digit 2 items ahead.
+     • 1212 produces 6: the list contains 4 items, and all four digits match
+       the digit 2 items ahead.
      • 1221 produces 0, because every comparison is between a 1 and a 2.
-     • 123425 produces 4, because both 2s match each other, but no other digit has a match.
+     • 123425 produces 4, because both 2s match each other, but no other digit
+       has a match.
      • 123123 produces 12.
      • 12131415 produces 4.
 
    What is the solution to your new captcha?
 
-   Your puzzle answer was ____.
+   Your puzzle answer was 1194.
 
    Both parts of this puzzle are complete! They provide two gold stars: **
 
-   At this point, you should return to your advent calendar and try another puzzle.
+   At this point, you should return to your advent calendar and try another
+   puzzle.
 
    If you still want to see it, you can get your puzzle input.
 

2017/day02/problem

@@ -29,7 +29,7 @@ Advent of Code
 
    What is the checksum for the spreadsheet in your puzzle input?
 
-   Your puzzle answer was ____.
+   Your puzzle answer was 46402.
 
    The first half of this puzzle is complete! It provides one gold star: *
 
@@ -66,9 +66,7 @@ Advent of Code
 
    Although it hasn't changed, you can still get your puzzle input.
 
-   Answer: _____________________
+   Answer: 265
-
-   You can also [Shareon Twitter Google+ Reddit] this puzzle.
 
 References
 

2017/day03/problem

@@ -31,7 +31,7 @@ Advent of Code
    How many steps are required to carry the data from the square identified in
    your puzzle input all the way to the access port?
 
-   Your puzzle answer was ____.
+   Your puzzle answer was 430.
 
 --- Part Two ---
 
@@ -63,7 +63,7 @@ Advent of Code
 
    What is the first value written that is larger than your puzzle input?
 
-   Your puzzle answer was _______.
+   Your puzzle answer was 312453.
 
    Both parts of this puzzle are complete! They provide two gold stars: **
 

2017/day04/problem

@@ -21,7 +21,7 @@ Advent of Code
    The system's full passphrase list is available as your
    puzzle input. How many passphrases are valid?
 
-   Your puzzle answer was ____.
+   Your puzzle answer was 466.
 
 --- Part Two ---
 
@@ -45,7 +45,7 @@ Advent of Code
    Under this new system policy, how many passphrases are
    valid?
 
-   Your puzzle answer was ____.
+   Your puzzle answer was 251.
 
    Both parts of this puzzle are complete! They provide two
    gold stars: **

2017/day05/problem

@@ -38,7 +38,7 @@ Advent of Code
 
    How many steps does it take to reach the exit?
 
-   Your puzzle answer was _______.
+   Your puzzle answer was 343364.
 
 --- Part Two ---
 
@@ -50,7 +50,7 @@ Advent of Code
 
    How many steps does it now take to reach the exit?
 
-   Your puzzle answer was _________.
+   Your puzzle answer was 25071947.
 
    Both parts of this puzzle are complete! They provide two gold stars: **
 

2017/day06/problem

@@ -0,0 +1,91 @@
+Advent of Code
+
+--- Day 6: Memory Reallocation ---
+
+   A debugger program here is having an issue: it is trying to repair a memory
+   reallocation routine, but it keeps getting stuck in an infinite loop.
+
+   In this area, there are sixteen memory banks; each memory bank can hold any
+   number of blocks. The goal of the reallocation routine is to balance the
+   blocks between the memory banks.
+
+   The reallocation routine operates in cycles. In each cycle, it finds the
+   memory bank with the most blocks (ties won by the lowest-numbered memory
+   bank) and redistributes those blocks among the banks. To do this, it removes
+   all of the blocks from the selected bank, then moves to the next (by index)
+   memory bank and inserts one of the blocks. It continues doing this until it
+   runs out of blocks; if it reaches the last memory bank, it wraps around to
+   the first one.
+
+   The debugger would like to know how many redistributions can be done before
+   a blocks-in-banks configuration is produced that has been seen before.
+
+   For example, imagine a scenario with only four memory banks:
+
+     • The banks start with 0, 2, 7, and 0 blocks. The third bank has the most
+       blocks, so it is chosen for redistribution.
+
+     • Starting with the next bank (the fourth bank) and then continuing to the
+       first bank, the second bank, and so on, the 7 blocks are spread out over
+       the memory banks. The fourth, first, and second banks get two blocks each,
+       and the third bank gets one back. The final result looks like this: 2 4 1
+       2.
+
+     • Next, the second bank is chosen because it contains the most blocks
+       (four). Because there are four memory banks, each gets one block. The
+       result is: 3 1 2 3.
+
+     • Now, there is a tie between the first and fourth memory banks, both of
+       which have three blocks. The first bank wins the tie, and its three blocks
+       are distributed evenly over the other three banks, leaving it with none: 0
+       2 3 4.
+
+     • The fourth bank is chosen, and its four blocks are distributed such that
+       each of the four banks receives one: 1 3 4 1.
+
+     • The third bank is chosen, and the same thing happens: 2 4 1 2.
+
+   At this point, we've reached a state we've seen before: 2 4 1 2 was already
+   seen. The infinite loop is detected after the fifth block redistribution
+   cycle, and so the answer in this example is 5.
+
+   Given the initial block counts in your puzzle input, how many redistribution
+   cycles must be completed before a configuration is produced that has been
+   seen before?
+
+   Your puzzle answer was 12841.
+
+--- Part Two ---
+
+   Out of curiosity, the debugger would also like to know the size of the loop:
+   starting from a state that has already been seen, how many block
+   redistribution cycles must be performed before that same state is seen
+   again?
+
+   In the example above, 2 4 1 2 is seen again after four cycles, and so the
+   answer in that example would be 4.
+
+   How many cycles are in the infinite loop that arises from the configuration
+   in your puzzle input?
+
+   Your puzzle answer was 8038.
+
+   Both parts of this puzzle are complete! They provide two gold stars: **
+
+References
+
+   Visible links
+   . http://adventofcode.com/
+   . http://adventofcode.com/2017/about
+   . http://adventofcode.com/2017/support
+   . http://adventofcode.com/2017/events
+   . http://adventofcode.com/2017/settings
+   . http://adventofcode.com/2017/auth/logout
+   . http://adventofcode.com/2017
+   . http://adventofcode.com/2017
+   . http://adventofcode.com/2017/leaderboard
+   . http://adventofcode.com/2017/stats
+   . http://adventofcode.com/2017/sponsors
+   . http://adventofcode.com/2017/sponsors
+   . http://adventofcode.com/2017
+   . http://adventofcode.com/2017/day/6/input

2017/day07/problem

@@ -67,7 +67,7 @@ Advent of Code
    Before you're ready to help them, you need to make sure your information is
    correct. What is the name of the bottom program?
 
-   Your puzzle answer was ___________.
+   Your puzzle answer was gynfwly.
 
 --- Part Two ---
 
@@ -100,7 +100,7 @@ Advent of Code
    Given that exactly one program is the wrong weight, what would its weight
    need to be to balance the entire tower?
 
-   Your puzzle answer was ______.
+   Your puzzle answer was 1526.
 
    Both parts of this puzzle are complete! They provide two gold stars: **
 

2017/day08/problem

@@ -25,14 +25,14 @@ Advent of Code
 
    What is the largest value in any register after completing the instructions in your puzzle input?
 
-   Your puzzle answer was ____.
+   Your puzzle answer was 4877.
 
 --- Part Two ---
 
    To be safe, the CPU also needs to know the highest value held in any register during this process so that it can decide how much memory to allocate to these operations. For example, in the above
    instructions, the highest value ever held was 10 (in register c after the third instruction was evaluated).
 
-   Your puzzle answer was ____.
+   Your puzzle answer was 5471.
 
    Both parts of this puzzle are complete! They provide two gold stars: **
 

2017/day09/problem

@@ -53,7 +53,7 @@ Advent of Code
 
    What is the total score for all groups in your input?
 
-   Your puzzle answer was ______.
+   Your puzzle answer was 10820.
 
 --- Part Two ---
 
@@ -72,7 +72,7 @@ Advent of Code
 
    How many non-canceled characters are within the garbage in your puzzle input?
 
-   Your puzzle answer was ______.
+   Your puzzle answer was 5547.
 
    Both parts of this puzzle are complete! They provide two gold stars: **
 

2017/day10/problem

@@ -52,7 +52,7 @@ Advent of Code
    However, you should instead use the standard list size of 256 (with values 0 to 255) and the sequence of lengths in your puzzle input. Once this process is
    complete, what is the result of multiplying the first two numbers in the list?
 
-   Your puzzle answer was ________.
+   Your puzzle answer was 19591.
 
 --- Part Two ---
 
@@ -99,7 +99,7 @@ Advent of Code
    Treating your puzzle input as a string of ASCII characters, what is the Knot Hash of your puzzle input? Ignore any leading or trailing whitespace you might
    encounter.
 
-   Your puzzle answer was _______________________________________.
+   Your puzzle answer was 62e2204d2ca4f4924f6e7a80f1288786.
 
    Both parts of this puzzle are complete! They provide two gold stars: **
 

2017/day11/problem

@@ -0,0 +1,57 @@
+Advent of Code
+
+--- Day 11: Hex Ed ---
+
+   Crossing the bridge, you've barely reached the other side of the stream when a program comes up to you, clearly in distress. "It's my child process," she says, "he's gotten lost in an infinite grid!"
+
+   Fortunately for her, you have plenty of experience with infinite grids.
+
+   Unfortunately for you, it's a hex grid.
+
+   The hexagons ("hexes") in this grid are aligned such that adjacent hexes can be found to the north, northeast, southeast, south, southwest, and northwest:
+
+   \ n  /
+ nw +--+ ne
+   /    \
+ -+      +-
+   \    /
+ sw +--+ se
+   / s  \
+
+   You have the path the child process took. Starting where he started, you need to determine the fewest number of steps required to reach him. (A "step" means to move from the hex you are in to any adjacent hex.)
+
+   For example:
+
+     • ne,ne,ne is 3 steps away.
+     • ne,ne,sw,sw is 0 steps away (back where you started).
+     • ne,ne,s,s is 2 steps away (se,se).
+     • se,sw,se,sw,sw is 3 steps away (s,s,sw).
+
+   Your puzzle answer was 747.
+
+--- Part Two ---
+
+   How many steps away is the furthest he ever got from his starting position?
+
+   Your puzzle answer was 1544.
+
+   Both parts of this puzzle are complete! They provide two gold stars: **
+
+References
+
+   Visible links
+   . http://adventofcode.com/
+   . http://adventofcode.com/2017/about
+   . http://adventofcode.com/2017/support
+   . http://adventofcode.com/2017/events
+   . http://adventofcode.com/2017/settings
+   . http://adventofcode.com/2017/auth/logout
+   . http://adventofcode.com/2017
+   . http://adventofcode.com/2017
+   . http://adventofcode.com/2017/leaderboard
+   . http://adventofcode.com/2017/stats
+   . http://adventofcode.com/2017/sponsors
+   . http://adventofcode.com/2017/sponsors
+   . https://en.wikipedia.org/wiki/Hexagonal_tiling
+   . http://adventofcode.com/2017
+   . http://adventofcode.com/2017/day/11/input

2017/day12/problem

@@ -42,7 +42,7 @@ Advent of Code
 
    How many programs are in the group that contains program ID 0?
 
-   Your puzzle answer was _____.
+   Your puzzle answer was 378.
 
    The first half of this puzzle is complete! It provides one gold star: *
 
@@ -62,7 +62,7 @@ Advent of Code
 
    Although it hasn't changed, you can still get your puzzle input.
 
-   Answer: _____________________
+   Answer: 204
 
 References
 

2017/day13/problem

@@ -184,7 +184,7 @@ Advent of Code
    Given the details of the firewall you've recorded, if you leave immediately, what is the severity of
    your whole trip?
 
-   Your puzzle answer was _______.
+   Your puzzle answer was 2508.
 
    The first half of this puzzle is complete! It provides one gold star: *
 
@@ -311,7 +311,7 @@ Advent of Code
 
    Although it hasn't changed, you can still get your puzzle input.
 
-   Answer: _____________________ [ [Submit] ]
+   Answer: 3913186
 
 References
 

2017/day14/problem

@@ -37,7 +37,7 @@ Advent of Code
 
    Given your actual key string, how many squares are used?
 
-   Your puzzle answer was ________.
+   Your puzzle answer was 8148.
 
 --- Part Two ---
 
@@ -62,7 +62,7 @@ Advent of Code
 
    How many regions are present given your key string?
 
-   Your puzzle answer was _____.
+   Your puzzle answer was 1180.
 
    Both parts of this puzzle are complete! They provide two gold stars: **
 

2017/day14gui/main.go

@@ -0,0 +1,476 @@
+package main
+
+/* OpenGL & Go Tutorial
+ * https://kylewbanks.com/blog/tutorial-opengl-with-golang-part-1-hello-opengl
+ *
+ * Vertex/Fragment Shader Explanation
+ * https://www.quora.com/What-is-a-vertex-shader-and-what-is-a-fragment-shader/answer/Harold-Serrano?srid=aVb
+ */
+
+import (
+	"bufio"
+	"fmt"
+	"log"
+	"math/rand"
+	"os"
+	"runtime"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/go-gl/gl/v2.1/gl"
+	"github.com/go-gl/glfw/v3.1/glfw"
+)
+
+// gl_Position = vec4(vp, 1.0);
+const (
+	width              = 500
+	height             = 500
+	vertexShaderSource = `
+		#version 410
+		in vec3 vp;
+		void main() {
+			gl_Position = vec4(vp, 1.0);
+		}
+	` + "\x00"
+	fragmentShaderSource = `
+		#version 410
+		out vec4 frag_colour;
+		void main() {
+			frag_colour = vec4(1.0, 1.0, 1.0, 1.0);
+		}
+	` + "\x00"
+
+	rows = 128
+	cols = 128
+	fps  = 10
+
+	threshold = 0.15
+)
+
+var (
+	square = []float32{
+		-0.5, 0.5, 0,
+		-0.5, -0.5, 0,
+		0.5, -0.5, 0,
+
+		-0.5, 0.5, 0,
+		0.5, 0.5, 0,
+		0.5, -0.5, 0,
+	}
+)
+
+var diskGrid map[string]bool
+var groups map[string]int
+var inp string
+
+func init() {
+	runtime.LockOSThread()
+
+	inp = "vbqugkhl" // My puzzle input
+	if len(os.Args) > 1 {
+		inp = os.Args[1]
+	}
+}
+
+func main() {
+	diskGrid = make(map[string]bool)
+	groups = make(map[string]int)
+
+	in := inp
+	window := initGlfw()
+	defer glfw.Terminate()
+
+	program := initOpenGL()
+
+	log.Println("Building DiskGrid...")
+	var grpCnt int
+	for i := 0; i < 128; i++ {
+		row := GetBinaryString(KnotHash(fmt.Sprintf("%s-%d", in, i)))
+		for j := range row {
+			diskGrid[cs(i, j)] = (row[j] == '1')
+			if row[j] == '1' {
+				groups[cs(i, j)] = grpCnt
+				grpCnt++
+			}
+		}
+	}
+
+	cells := makeCells()
+	for !window.ShouldClose() {
+		t := time.Now()
+
+		//ReduceGroups()
+
+		for x := range cells {
+			for _, c := range cells[x] {
+				c.checkState(cells)
+			}
+		}
+
+		draw(cells, window, program)
+
+		time.Sleep(time.Second/time.Duration(fps) - time.Since(t))
+	}
+}
+
+// initGlfw initializes glfw and returns a Window to use.
+func initGlfw() *glfw.Window {
+	if err := glfw.Init(); err != nil {
+		panic(err)
+	}
+
+	glfw.WindowHint(glfw.Resizable, glfw.False)
+	glfw.WindowHint(glfw.ContextVersionMajor, 4)
+	glfw.WindowHint(glfw.ContextVersionMinor, 1)
+	glfw.WindowHint(glfw.OpenGLProfile, glfw.OpenGLCoreProfile)
+	glfw.WindowHint(glfw.OpenGLForwardCompatible, glfw.True)
+
+	window, err := glfw.CreateWindow(width, height, "Conway's Game of Life", nil, nil)
+	if err != nil {
+		panic(err)
+	}
+	window.MakeContextCurrent()
+
+	return window
+}
+
+// initOpenGL initializes OpenGL and returns an initialized program.
+func initOpenGL() uint32 {
+	if err := gl.Init(); err != nil {
+		panic(err)
+	}
+	version := gl.GoStr(gl.GetString(gl.VERSION))
+	log.Println("OpenGL version", version)
+
+	vertexShader, err := compileShader(vertexShaderSource, gl.VERTEX_SHADER)
+	if err != nil {
+		panic(err)
+	}
+	fragmentShader, err := compileShader(fragmentShaderSource, gl.FRAGMENT_SHADER)
+	if err != nil {
+		panic(err)
+	}
+
+	prog := gl.CreateProgram()
+	gl.AttachShader(prog, vertexShader)
+	gl.AttachShader(prog, fragmentShader)
+	gl.LinkProgram(prog)
+	return prog
+}
+
+func draw(cells [][]*cell, window *glfw.Window, program uint32) {
+	gl.Clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT)
+	gl.UseProgram(program)
+
+	for x := range cells {
+		for _, c := range cells[x] {
+			c.draw()
+		}
+	}
+
+	glfw.PollEvents()
+	window.SwapBuffers()
+}
+
+// makeVao initializes and returns a vertex array from the points provided.
+func makeVao(points []float32) uint32 {
+	var vbo uint32
+	gl.GenBuffers(1, &vbo)
+	gl.BindBuffer(gl.ARRAY_BUFFER, vbo)
+	gl.BufferData(gl.ARRAY_BUFFER, 4*len(points), gl.Ptr(points), gl.STATIC_DRAW)
+
+	var vao uint32
+	gl.GenVertexArrays(1, &vao)
+	gl.BindVertexArray(vao)
+	gl.EnableVertexAttribArray(0)
+	gl.BindBuffer(gl.ARRAY_BUFFER, vbo)
+	gl.VertexAttribPointer(0, 3, gl.FLOAT, false, 0, nil)
+
+	return vao
+}
+
+func compileShader(source string, shaderType uint32) (uint32, error) {
+	shader := gl.CreateShader(shaderType)
+
+	csources, free := gl.Strs(source)
+	gl.ShaderSource(shader, 1, csources, nil)
+	free()
+	gl.CompileShader(shader)
+
+	var status int32
+	gl.GetShaderiv(shader, gl.COMPILE_STATUS, &status)
+	if status == gl.FALSE {
+		var logLength int32
+		gl.GetShaderiv(shader, gl.INFO_LOG_LENGTH, &logLength)
+
+		log := strings.Repeat("\x00", int(logLength+1))
+		gl.GetShaderInfoLog(shader, logLength, nil, gl.Str(log))
+
+		return 0, fmt.Errorf("failed to compile %v: %v", source, log)
+	}
+
+	return shader, nil
+}
+
+func makeCells() [][]*cell {
+	rand.Seed(time.Now().UnixNano())
+
+	cells := make([][]*cell, rows, rows)
+	for x := 0; x < rows; x++ {
+		for y := 0; y < cols; y++ {
+			var gr int
+			var ok bool
+			c := newCell(x, y)
+			if gr, ok = groups[cs(x, y)]; ok {
+				c.group = gr
+			}
+
+			c.alive = rand.Float64() < threshold
+			c.aliveNext = c.alive
+
+			cells[x] = append(cells[x], c)
+		}
+	}
+
+	return cells
+}
+
+type cell struct {
+	drawable uint32
+
+	alive     bool
+	aliveNext bool
+
+	group int
+
+	x int
+	y int
+}
+
+func newCell(x, y int) *cell {
+	points := make([]float32, len(square), len(square))
+	copy(points, square)
+
+	for i := 0; i < len(points); i++ {
+		var position float32
+		var size float32
+		switch i % 3 {
+		case 0:
+			size = 1.0 / float32(cols)
+			position = float32(x) * size
+		case 1:
+			size = 1.0 / float32(rows)
+			position = float32(y) * size
+		default:
+			continue
+		}
+
+		if points[i] < 0 {
+			points[i] = (position * 2) - 1
+		} else {
+			points[i] = ((position + size) * 2) - 1
+		}
+	}
+
+	return &cell{
+		drawable: makeVao(points),
+		x:        x,
+		y:        y,
+		group:    0,
+	}
+}
+
+func (c *cell) draw() {
+	if !c.alive {
+		return
+	}
+
+	gl.BindVertexArray(c.drawable)
+	gl.DrawArrays(gl.TRIANGLES, 0, int32(len(square)/3))
+}
+
+// checkState determines the state of the cell for the next tick of the game
+func (c *cell) checkState(cells [][]*cell) {
+	c.alive = c.aliveNext
+	c.aliveNext = c.alive
+
+	liveCount := c.liveNeighbors(cells)
+	if c.alive {
+		// 1. Any live cell with fewer than two live neighbours dies, as if caused by underpopulation
+		if liveCount < 2 {
+			c.alive = false
+		}
+
+		// 2. Any live cell with two or three live neighbors lives on to the next generation
+		if liveCount == 2 || liveCount == 3 {
+			c.aliveNext = true
+		}
+
+		// 3. Any live cell with more than three live neighbors dies, as if by overpopulation
+		if liveCount > 3 {
+			c.aliveNext = false
+		}
+	} else {
+		// 4. Any dead cell with exactly three live neighbors becomes a live cell, as if by reproduction
+		if liveCount == 3 {
+			c.aliveNext = true
+		}
+	}
+}
+
+// liveNeighbors returns the number of live neighbors for a cell
+func (c *cell) liveNeighbors(cells [][]*cell) int {
+	var liveCount int
+	add := func(x, y int) {
+		// If we're at an edge, check the other side of the board.
+		if x == len(cells) {
+			x = 0
+		} else if x == -1 {
+			x = len(cells) - 1
+		}
+		if y == len(cells[x]) {
+			y = 0
+		} else if y == -1 {
+			y = len(cells[x]) - 1
+		}
+
+		if cells[x][y].alive {
+			liveCount++
+		}
+	}
+
+	add(c.x-1, c.y)   // To the left
+	add(c.x+1, c.y)   // To the right
+	add(c.x, c.y+1)   // Up
+	add(c.x, c.y-1)   // Down
+	add(c.x-1, c.y+1) // Top-Left
+	add(c.x+1, c.y+1) // Top-Right
+	add(c.x-1, c.y-1) // Bottom-Left
+	add(c.x+1, c.y-1) // Bottom-Right
+
+	return liveCount
+}
+
+func ReduceGroups() bool {
+	var ret bool
+	for x := 0; x < 128; x++ {
+		for y := 0; y < 128; y++ {
+			if oV, oOk := diskGrid[cs(x, y)]; oOk && oV {
+				if dV, dOk := diskGrid[cs(x, y-1)]; dOk && dV && groups[cs(x, y-1)] != groups[cs(x, y)] {
+					CombineBlockGroups(cs(x, y), cs(x, y-1))
+					ret = true
+				}
+				if dV, dOk := diskGrid[cs(x-1, y)]; dOk && dV && groups[cs(x-1, y)] != groups[cs(x, y)] {
+					CombineBlockGroups(cs(x, y), cs(x-1, y))
+					ret = true
+				}
+				if dV, dOk := diskGrid[cs(x+1, y)]; dOk && dV && groups[cs(x+1, y)] != groups[cs(x, y)] {
+					CombineBlockGroups(cs(x+1, y), cs(x, y))
+					ret = true
+				}
+				if dV, dOk := diskGrid[cs(x, y+1)]; dOk && dV && groups[cs(x, y+1)] != groups[cs(x, y)] {
+					CombineBlockGroups(cs(x, y+1), cs(x, y))
+					ret = true
+				}
+			}
+		}
+	}
+	return ret
+}
+
+func CombineBlockGroups(b1, b2 string) {
+	if groups[b1] < groups[b2] {
+		groups[b1] = groups[b2]
+	} else {
+		groups[b2] = groups[b1]
+	}
+}
+
+// Get a map coordinate string for x, y
+func cs(x, y int) string {
+	return fmt.Sprint(x, "-", y)
+}
+
+// Get the x, y coordinate from a string
+func sc(c string) (int, int) {
+	pts := strings.Split(c, "-")
+	return Atoi(pts[0]), Atoi(pts[1])
+}
+
+func KnotHash(in string) string {
+	var idx, skip int
+	var list []int
+	for i := 0; i < 256; i++ {
+		list = append(list, i)
+	}
+	inpBts := []byte(in)
+	inpBts = append(inpBts, []byte{17, 31, 73, 47, 23}...)
+	for j := 0; j < 64; j++ {
+		for i := range inpBts {
+			idx, skip, list = khRound(int(inpBts[i]), idx, skip, list)
+		}
+	}
+	// Now calculate the dense hash
+	var dense []byte
+	for i := 0; i < len(list); i += 16 {
+		dense = append(dense, xorList(list[i:i+16]))
+	}
+	return fmt.Sprintf("%x", dense)
+}
+
+func khRound(i, idx, skip int, list []int) (int, int, []int) {
+	// if idx+i overflows, pull from the front
+	var revList []int
+	for j := idx; j < idx+i; j++ {
+		revList = append([]int{list[j%256]}, revList...)
+	}
+	for j := 0; j < len(revList); j++ {
+		list[(idx+j)%256] = revList[j]
+	}
+
+	idx += i + skip
+	skip++
+	return idx, skip, list
+}
+
+func xorList(in []int) byte {
+	var ret byte
+	for i := range in {
+		ret ^= byte(in[i])
+	}
+	return ret
+}
+
+func GetBinaryString(in string) string {
+	var bin string
+	for i := range in {
+		var v int
+		if in[i] >= '0' && in[i] <= '9' {
+			v = int(in[i] - '0')
+		} else if in[i] >= 'a' && in[i] <= 'f' {
+			v = int(in[i] - 'a' + 10)
+		}
+		nibble := fmt.Sprintf("%04s", strconv.FormatInt(int64(v), 2))
+		bin += nibble
+	}
+	return bin
+}
+
+func StdinToString() string {
+	var input string
+	scanner := bufio.NewScanner(os.Stdin)
+	for scanner.Scan() {
+		input = scanner.Text()
+	}
+	return input
+}
+
+func Atoi(i string) int {
+	var ret int
+	var err error
+	if ret, err = strconv.Atoi(i); err != nil {
+		log.Fatal("Invalid Atoi")
+	}
+	return ret
+}

2017/day15/problem

@@ -0,0 +1,153 @@
+Advent of Code
+
+--- Day 15: Dueling Generators ---
+
+   Here, you encounter a pair of dueling generators. The generators, called
+   generator A and generator B, are trying to agree on a sequence of numbers.
+   However, one of them is malfunctioning, and so the sequences don't always
+   match.
+
+   As they do this, a judge waits for each of them to generate its next value,
+   compares the lowest 16 bits of both values, and keeps track of the number of
+   times those parts of the values match.
+
+   The generators both work on the same principle. To create its next value, a
+   generator will take the previous value it produced, multiply it by a factor
+   (generator A uses 16807; generator B uses 48271), and then keep the
+   remainder of dividing that resulting product by 2147483647. That final
+   remainder is the value it produces next.
+
+   To calculate each generator's first value, it instead uses a specific
+   starting value as its "previous value" (as listed in your puzzle input).
+
+   For example, suppose that for starting values, generator A uses 65, while
+   generator B uses 8921. Then, the first five pairs of generated values are:
+
+ --Gen. A--  --Gen. B--
+    1092455   430625591
+ 1181022009  1233683848
+  245556042  1431495498
+ 1744312007   137874439
+ 1352636452   285222916
+
+   In binary, these pairs are (with generator A's value first in each pair):
+
+ 00000000000100001010101101100111
+ 00011001101010101101001100110111
+
+ 01000110011001001111011100111001
+ 01001001100010001000010110001000
+
+ 00001110101000101110001101001010
+ 01010101010100101110001101001010
+
+ 01100111111110000001011011000111
+ 00001000001101111100110000000111
+
+ 01010000100111111001100000100100
+ 00010001000000000010100000000100
+
+   Here, you can see that the lowest (here, rightmost) 16 bits of the third
+   value match: 1110001101001010. Because of this one match, after processing
+   these five pairs, the judge would have added only 1 to its total.
+
+   To get a significant sample, the judge would like to consider 40 million
+   pairs. (In the example above, the judge would eventually find a total of 588
+   pairs that match in their lowest 16 bits.)
+
+   After 40 million pairs, what is the judge's final count?
+
+   Your puzzle answer was 626.
+
+--- Part Two ---
+
+   In the interest of trying to align a little better, the generators get more
+   picky about the numbers they actually give to the judge.
+
+   They still generate values in the same way, but now they only hand a value
+   to the judge when it meets their criteria:
+
+     • Generator A looks for values that are multiples of 4.
+     • Generator B looks for values that are multiples of 8.
+
+   Each generator functions completely independently: they both go through
+   values entirely on their own, only occasionally handing an acceptable value
+   to the judge, and otherwise working through the same sequence of values as
+   before until they find one.
+
+   The judge still waits for each generator to provide it with a value before
+   comparing them (using the same comparison method as before). It keeps track
+   of the order it receives values; the first values from each generator are
+   compared, then the second values from each generator, then the third values,
+   and so on.
+
+   Using the example starting values given above, the generators now produce
+   the following first five values each:
+
+ --Gen. A--  --Gen. B--
+ 1352636452  1233683848
+ 1992081072   862516352
+  530830436  1159784568
+ 1980017072  1616057672
+  740335192   412269392
+
+   These values have the following corresponding binary values:
+
+ 01010000100111111001100000100100
+ 01001001100010001000010110001000
+
+ 01110110101111001011111010110000
+ 00110011011010001111010010000000
+
+ 00011111101000111101010001100100
+ 01000101001000001110100001111000
+
+ 01110110000001001010100110110000
+ 01100000010100110001010101001000
+
+ 00101100001000001001111001011000
+ 00011000100100101011101101010000
+
+   Unfortunately, even though this change makes more bits similar on average,
+   none of these values' lowest 16 bits match. Now, it's not until the 1056th
+   pair that the judge finds the first match:
+
+ --Gen. A--  --Gen. B--
+ 1023762912   896885216
+
+ 00111101000001010110000111100000
+ 00110101011101010110000111100000
+
+   This change makes the generators much slower, and the judge is getting
+   impatient; it is now only willing to consider 5 million pairs. (Using the
+   values from the example above, after five million pairs, the judge would
+   eventually find a total of 309 pairs that match in their lowest 16 bits.)
+
+   After 5 million pairs, but using this new generator logic, what is the
+   judge's final count?
+
+   Your puzzle answer was 306.
+
+   Both parts of this puzzle are complete! They provide two gold stars: **
+
+   At this point, all that is left is for you to admire your advent calendar.
+
+   If you still want to see it, you can get your puzzle input.
+
+References
+
+   Visible links
+   . http://adventofcode.com/
+   . http://adventofcode.com/2017/about
+   . http://adventofcode.com/2017/support
+   . http://adventofcode.com/2017/events
+   . http://adventofcode.com/2017/settings
+   . http://adventofcode.com/2017/auth/logout
+   . http://adventofcode.com/2017
+   . http://adventofcode.com/2017
+   . http://adventofcode.com/2017/leaderboard
+   . http://adventofcode.com/2017/stats
+   . http://adventofcode.com/2017/sponsors
+   . http://adventofcode.com/2017/sponsors
+   . http://adventofcode.com/2017
+   . http://adventofcode.com/2017/day/15/input

2017/day16/problem

@@ -30,7 +30,7 @@ Advent of Code
    You watch the dance for a while and record their dance moves (your puzzle
    input). In what order are the programs standing after their dance?
 
-   Your puzzle answer was ________________.
+   Your puzzle answer was bkgcdefiholnpmja.
 
 --- Part Two ---
 
@@ -50,7 +50,7 @@ Advent of Code
 
    In what order are the programs standing after their billion dances?
 
-   Your puzzle answer was ________________.
+   Your puzzle answer was knmdfoijcbpghlea.
 
    Both parts of this puzzle are complete! They provide two gold stars: **
 

2017/day17/problem

@@ -56,7 +56,7 @@ Advent of Code
 
    What is the value after 2017 in your completed circular buffer?
 
-   Your puzzle answer was ________.
+   Your puzzle answer was 1642.
 
 --- Part Two ---
 
@@ -75,7 +75,7 @@ Advent of Code
 
    What is the value after 0 the moment 50000000 is inserted?
 
-   Your puzzle answer was _____________.
+   Your puzzle answer was 301.
 
    Both parts of this puzzle are complete! They provide two gold stars: **
 

2017/day18/problem

@@ -44,7 +44,7 @@ Advent of Code
 
    What is the value of the recovered frequency (the value of the most recently played sound) the first time a rcv instruction is executed with a non-zero value?
 
-   Your puzzle answer was _________.
+   Your puzzle answer was 1187.
 
 --- Part Two ---
 
@@ -80,7 +80,7 @@ Advent of Code
 
    Once both of your programs have terminated (regardless of what caused them to do so), how many times did program 1 send a value?
 
-   Your puzzle answer was _______.
+   Your puzzle answer was 5969.
 
    Both parts of this puzzle are complete! They provide two gold stars: **
 

2017/day19/problem

@@ -35,7 +35,7 @@ Advent of Code
    would see them) if it follows the path? (The routing diagram is very wide; make sure you view it without line
    wrapping.)
 
-   Your puzzle answer was __________________.
+   Your puzzle answer was RUEDAHWKSM.
 
 --- Part Two ---
 
@@ -66,7 +66,7 @@ Advent of Code
 
    How many steps does the packet need to go?
 
-   Your puzzle answer was _________.
+   Your puzzle answer was 17264.
 
    Both parts of this puzzle are complete! They provide two gold stars: **
 
@@ -89,7 +89,5 @@ References
    . http://adventofcode.com/2017/stats
    . http://adventofcode.com/2017/sponsors
    . http://adventofcode.com/2017/sponsors
-   . https://teespring.com/advent-of-code
-   . https://teespring.com/advent-of-code-eu
    . http://adventofcode.com/2017
    . http://adventofcode.com/2017/day/19/input

2017/day20/problem

@@ -54,7 +54,7 @@ Advent of Code
    Which particle will stay closest to position <0,0,0> in the
    long term?
 
-   Your puzzle answer was _______.
+   Your puzzle answer was 119.
 
    The first half of this puzzle is complete! It provides one
    gold star: *
@@ -99,7 +99,7 @@ Advent of Code
    Although it hasn't changed, you can still get your puzzle
    input.
 
-   Answer: _____________________
+   Answer: 471
 
 References
 

2017/day21/problem

@@ -0,0 +1,142 @@
+Advent of Code
+
+--- Day 21: Fractal Art ---
+
+   You find a program trying to generate some art. It uses a strange process
+   that involves repeatedly enhancing the detail of an image through a set of
+   rules.
+
+   The image consists of a two-dimensional square grid of pixels that are
+   either on (#) or off (.). The program always begins with this pattern:
+
+ .#.
+ ..#
+ ###
+
+   Because the pattern is both 3 pixels wide and 3 pixels tall, it is said to
+   have a size of 3.
+
+   Then, the program repeats the following process:
+
+     • If the size is evenly divisible by 2, break the pixels up into 2x2
+     squares, and convert each 2x2 square into a 3x3 square by following the
+     corresponding enhancement rule.
+
+     • Otherwise, the size is evenly divisible by 3; break the pixels up into
+     3x3 squares, and convert each 3x3 square into a 4x4 square by following
+     the corresponding enhancement rule.
+
+   Because each square of pixels is replaced by a larger one, the image gains
+   pixels and so its size increases.
+
+   The artist's book of enhancement rules is nearby (your puzzle input);
+   however, it seems to be missing rules. The artist explains that sometimes,
+   one must rotate or flip the input pattern to find a match. (Never rotate or
+   flip the output pattern, though.) Each pattern is written concisely: rows
+   are listed as single units, ordered top-down, and separated by slashes. For
+   example, the following rules correspond to the adjacent patterns:
+
+ ../.#  =  ..
+           .#
+
+                 .#.
+ .#./..#/###  =  ..#
+                 ###
+
+                         #..#
+ #..#/..../#..#/.##.  =  ....
+                         #..#
+                         .##.
+
+   When searching for a rule to use, rotate and flip the pattern as necessary.
+   For example, all of the following patterns match the same rule:
+
+ .#.   .#.   #..   ###
+ ..#   #..   #.#   ..#
+ ###   ###   ##.   .#.
+
+   Suppose the book contained the following two rules:
+
+ ../.# => ##./#../...
+ .#./..#/### => #..#/..../..../#..#
+
+   As before, the program begins with this pattern:
+
+ .#.
+ ..#
+ ###
+
+   The size of the grid (3) is not divisible by 2, but it is divisible by 3. It
+   divides evenly into a single square; the square matches the second rule,
+   which produces:
+
+ #..#
+ ....
+ ....
+ #..#
+
+   The size of this enhanced grid (4) is evenly divisible by 2, so that rule is
+   used. It divides evenly into four squares:
+
+ #.|.#
+ ..|..
+ --+--
+ ..|..
+ #.|.#
+
+   Each of these squares matches the same rule (../.# => ##./#../...), three of
+   which require some flipping and rotation to line up with the rule. The
+   output for the rule is the same in all four cases:
+
+ ##.|##.
+ #..|#..
+ ...|...
+ ---+---
+ ##.|##.
+ #..|#..
+ ...|...
+
+   Finally, the squares are joined into a new grid:
+
+ ##.##.
+ #..#..
+ ......
+ ##.##.
+ #..#..
+ ......
+
+   Thus, after 2 iterations, the grid contains 12 pixels that are on.
+
+   How many pixels stay on after 5 iterations?
+
+   Your puzzle answer was 164.
+
+--- Part Two ---
+
+   How many pixels stay on after 18 iterations?
+
+   Your puzzle answer was 2355110.
+
+   Both parts of this puzzle are complete! They provide two gold stars: **
+
+   At this point, all that is left is for you to admire your advent calendar.
+
+   If you still want to see it, you can get your puzzle input.
+
+References
+
+   Visible links
+   . http://adventofcode.com/
+   . http://adventofcode.com/2017/about
+   . http://adventofcode.com/2017/support
+   . http://adventofcode.com/2017/events
+   . http://adventofcode.com/2017/settings
+   . http://adventofcode.com/2017/auth/logout
+   . http://adventofcode.com/2017
+   . http://adventofcode.com/2017
+   . http://adventofcode.com/2017/leaderboard
+   . http://adventofcode.com/2017/stats
+   . http://adventofcode.com/2017/sponsors
+   . http://adventofcode.com/2017/sponsors
+   . http://adventofcode.com/2017
+   . http://adventofcode.com/2017/day/21/input

2017/day22/problem

@@ -122,7 +122,7 @@ Advent of Code
    Given your actual map, after 10000 bursts of activity, how many bursts cause
    a node to become infected? (Do not count nodes that begin infected.)
 
-   Your puzzle answer was _______.
+   Your puzzle answer was 5348.
 
    The first half of this puzzle is complete! It provides one gold star: *
 
@@ -241,7 +241,7 @@ Advent of Code
 
    Although it hasn't changed, you can still get your puzzle input.
 
-   Answer: _____________________ [ [Submit] ]
+   Answer: 2512225
 
 References
 

2017/day23/problem

@@ -0,0 +1,82 @@
+Advent of Code
+
+--- Day 23: Coprocessor Conflagration ---
+
+   You decide to head directly to the CPU and fix the printer from there. As
+   you get close, you find an experimental coprocessor doing so much work that
+   the local programs are afraid it will halt and catch fire. This would cause
+   serious issues for the rest of the computer, so you head in and see what you
+   can do.
+
+   The code it's running seems to be a variant of the kind you saw recently on
+   that tablet. The general functionality seems very similar, but some of the
+   instructions are different:
+
+     • set X Y sets register X to the value of Y.
+
+     • sub X Y decreases register X by the value of Y.
+
+     • mul X Y sets register X to the result of multiplying the value contained
+       in register X by the value of Y.
+
+     • jnz X Y jumps with an offset of the value of Y, but only if the value of
+       X is not zero. (An offset of 2 skips the next instruction, an offset of -1
+       jumps to the previous instruction, and so on.)
+
+     Only the instructions listed above are used. The eight registers here,
+     named a through h, all start at 0.
+
+   The coprocessor is currently set to some kind of debug mode, which allows
+   for testing, but prevents it from doing any meaningful work.
+
+   If you run the program (your puzzle input), how many times is the mul
+   instruction invoked?
+
+   Your puzzle answer was 9409.
+
+--- Part Two ---
+
+   Now, it's time to fix the problem.
+
+   The debug mode switch is wired directly to register a. You flip the switch,
+   which makes register a now start at 1 when the program is executed.
+
+   Immediately, the coprocessor begins to overheat. Whoever wrote this program
+   obviously didn't choose a very efficient implementation. You'll need to
+   optimize the program if it has any hope of completing before Santa needs
+   that printer working.
+
+   The coprocessor's ultimate goal is to determine the final value left in
+   register h once the program completes. Technically, if it had that... it
+   wouldn't even need to run the program.
+
+   After setting register a to 1, if the program were to run to completion,
+   what value would be left in register h?
+
+   Your puzzle answer was 913.
+
+   Both parts of this puzzle are complete! They provide two gold stars: **
+
+   At this point, all that is left is for you to admire your advent calendar.
+
+   If you still want to see it, you can get your puzzle input.
+
+References
+
+   Visible links
+   . http://adventofcode.com/
+   . http://adventofcode.com/2017/about
+   . http://adventofcode.com/2017/support
+   . http://adventofcode.com/2017/events
+   . http://adventofcode.com/2017/settings
+   . http://adventofcode.com/2017/auth/logout
+   . http://adventofcode.com/2017
+   . http://adventofcode.com/2017
+   . http://adventofcode.com/2017/leaderboard
+   . http://adventofcode.com/2017/stats
+   . http://adventofcode.com/2017/sponsors
+   . http://adventofcode.com/2017/sponsors
+   . https://en.wikipedia.org/wiki/Halt_and_Catch_Fire
+   . http://adventofcode.com/2017/day/18
+   . http://adventofcode.com/2017
+   . http://adventofcode.com/2017/day/23/input

2017/day24/problem

@@ -0,0 +1,104 @@
+Advent of Code
+
+--- Day 24: Electromagnetic Moat ---
+
+   The CPU itself is a large, black building surrounded by a bottomless pit.
+   Enormous metal tubes extend outward from the side of the building at regular
+   intervals and descend down into the void. There's no way to cross, but you
+   need to get inside.
+
+   No way, of course, other than building a bridge out of the magnetic
+   components strewn about nearby.
+
+   Each component has two ports, one on each end. The ports come in all
+   different types, and only matching types can be connected. You take an
+   inventory of the components by their port types (your puzzle input). Each
+   port is identified by the number of pins it uses; more pins mean a stronger
+   connection for your bridge. A 3/7 component, for example, has a type-3 port
+   on one side, and a type-7 port on the other.
+
+   Your side of the pit is metallic; a perfect surface to connect a magnetic,
+   zero-pin port. Because of this, the first port you use must be of type 0. It
+   doesn't matter what type of port you end with; your goal is just to make the
+   bridge as strong as possible.
+
+   The strength of a bridge is the sum of the port types in each component. For
+   example, if your bridge is made of components 0/3, 3/7, and 7/4, your bridge
+   has a strength of 0+3 + 3+7 + 7+4 = 24.
+
+   For example, suppose you had the following components:
+
+ 0/2
+ 2/2
+ 2/3
+ 3/4
+ 3/5
+ 0/1
+ 10/1
+ 9/10
+
+   With them, you could make the following valid bridges:
+
+     • 0/1
+     • 0/1--10/1
+     • 0/1--10/1--9/10
+     • 0/2
+     • 0/2--2/3
+     • 0/2--2/3--3/4
+     • 0/2--2/3--3/5
+     • 0/2--2/2
+     • 0/2--2/2--2/3
+     • 0/2--2/2--2/3--3/4
+     • 0/2--2/2--2/3--3/5
+
+   (Note how, as shown by 10/1, order of ports within a component doesn't
+   matter. However, you may only use each port on a component once.)
+
+   Of these bridges, the strongest one is 0/1--10/1--9/10; it has a strength of
+   0+1 + 1+10 + 10+9 = 31.
+
+   What is the strength of the strongest bridge you can make with the
+   components you have available?
+
+   Your puzzle answer was 1868.
+
+--- Part Two ---
+
+   The bridge you've built isn't long enough; you can't jump the rest of the way.
+
+   In the example above, there are two longest bridges:
+
+     • 0/2--2/2--2/3--3/4
+     • 0/2--2/2--2/3--3/5
+
+   Of them, the one which uses the 3/5 component is stronger; its strength is
+   0+2 + 2+2 + 2+3 + 3+5 = 19.
+
+   What is the strength of the longest bridge you can make? If you can make
+   multiple bridges of the longest length, pick the strongest one.
+
+   Your puzzle answer was 1841.
+
+   Both parts of this puzzle are complete! They provide two gold stars: **
+
+   At this point, all that is left is for you to admire your advent calendar.
+
+   If you still want to see it, you can get your puzzle input.
+
+References
+
+   Visible links
+   . http://adventofcode.com/
+   . http://adventofcode.com/2017/about
+   . http://adventofcode.com/2017/support
+   . http://adventofcode.com/2017/events
+   . http://adventofcode.com/2017/settings
+   . http://adventofcode.com/2017/auth/logout
+   . http://adventofcode.com/2017
+   . http://adventofcode.com/2017
+   . http://adventofcode.com/2017/leaderboard
+   . http://adventofcode.com/2017/stats
+   . http://adventofcode.com/2017/sponsors
+   . http://adventofcode.com/2017/sponsors
+   . http://adventofcode.com/2017
+   . http://adventofcode.com/2017/day/24/input

2017/day25/problem

@@ -0,0 +1,139 @@
+Advent of Code
+
+--- Day 25: The Halting Problem ---
+
+   Following the twisty passageways deeper and deeper into the CPU, you finally
+   reach the core of the computer. Here, in the expansive central chamber, you
+   find a grand apparatus that fills the entire room, suspended nanometers
+   above your head.
+
+   You had always imagined CPUs to be noisy, chaotic places, bustling with
+   activity. Instead, the room is quiet, motionless, and dark.
+
+   Suddenly, you and the CPU's garbage collector startle each other. "It's not
+   often we get many visitors here!", he says. You inquire about the stopped
+   machinery.
+
+   "It stopped milliseconds ago; not sure why. I'm a garbage collector, not a
+   doctor." You ask what the machine is for.
+
+   "Programs these days, don't know their origins. That's the Turing machine!
+   It's what makes the whole computer work." You try to explain that Turing
+   machines are merely models of computation, but he cuts you off. "No, see,
+   that's just what they want you to think. Ultimately, inside every CPU,
+   there's a Turing machine driving the whole thing! Too bad this one's broken.
+   We're doomed!"
+
+   You ask how you can help. "Well, unfortunately, the only way to get the
+   computer running again would be to create a whole new Turing machine from
+   scratch, but there's no way you can-" He notices the look on your face,
+   gives you a curious glance, shrugs, and goes back to sweeping the floor.
+
+   You find the Turing machine blueprints (your puzzle input) on a tablet in a
+   nearby pile of debris. Looking back up at the broken Turing machine above,
+   you can start to identify its parts:
+
+     • A tape which contains 0 repeated infinitely to the left and right.
+
+     • A cursor, which can move left or right along the tape and read or write
+       values at its current position.
+
+     • A set of states, each containing rules about what to do based on the
+       current value under the cursor.
+
+   Each slot on the tape has two possible values: 0 (the starting value for all
+   slots) and 1. Based on whether the cursor is pointing at a 0 or a 1, the
+   current state says what value to write at the current position of the
+   cursor, whether to move the cursor left or right one slot, and which state
+   to use next.
+
+   For example, suppose you found the following blueprint:
+
+ Begin in state A.
+ Perform a diagnostic checksum after 6 steps.
+
+ In state A:
+   If the current value is 0:
+     - Write the value 1.
+     - Move one slot to the right.
+     - Continue with state B.
+   If the current value is 1:
+     - Write the value 0.
+     - Move one slot to the left.
+     - Continue with state B.
+
+ In state B:
+   If the current value is 0:
+     - Write the value 1.
+     - Move one slot to the left.
+     - Continue with state A.
+   If the current value is 1:
+     - Write the value 1.
+     - Move one slot to the right.
+     - Continue with state A.
+
+   Running it until the number of steps required to take the listed diagnostic
+   checksum would result in the following tape configurations (with the cursor
+   marked in square brackets):
+
+ ... 0  0  0 [0] 0  0 ... (before any steps; about to run state A)
+ ... 0  0  0  1 [0] 0 ... (after 1 step;     about to run state B)
+ ... 0  0  0 [1] 1  0 ... (after 2 steps;    about to run state A)
+ ... 0  0 [0] 0  1  0 ... (after 3 steps;    about to run state B)
+ ... 0 [0] 1  0  1  0 ... (after 4 steps;    about to run state A)
+ ... 0  1 [1] 0  1  0 ... (after 5 steps;    about to run state B)
+ ... 0  1  1 [0] 1  0 ... (after 6 steps;    about to run state A)
+
+   The CPU can confirm that the Turing machine is working by taking a
+   diagnostic checksum after a specific number of steps (given in the
+   blueprint). Once the specified number of steps have been executed, the
+   Turing machine should pause; once it does, count the number of times 1
+   appears on the tape. In the above example, the diagnostic checksum is 3.
+
+   Recreate the Turing machine and save the computer! What is the diagnostic
+   checksum it produces once it's working again?
+
+   Your puzzle answer was 5593.
+
+--- Part Two ---
+
+   The Turing machine, and soon the entire computer, springs back to life. A
+   console glows dimly nearby, awaiting your command.
+
+ > reboot printer
+ Error: That command requires priority 50. You currently have priority 0.
+ You must deposit 50 stars to increase your priority to the required level.
+
+   The console flickers for a moment, and then prints another message:
+
+ Star accepted.
+ You must deposit 49 stars to increase your priority to the required level.
+
+   The garbage collector winks at you, then continues sweeping.
+
+   If you like, you can [ [Reboot the Printer Again] ] .
+
+   Both parts of this puzzle are complete! They provide two gold stars: **
+
+   At this point, all that is left is for you to admire your advent calendar.
+
+   If you still want to see it, you can get your puzzle input.
+
+References
+
+   Visible links
+   . http://adventofcode.com/
+   . http://adventofcode.com/2017/about
+   . http://adventofcode.com/2017/support
+   . http://adventofcode.com/2017/events
+   . http://adventofcode.com/2017/settings
+   . http://adventofcode.com/2017/auth/logout
+   . http://adventofcode.com/2017
+   . http://adventofcode.com/2017
+   . http://adventofcode.com/2017/leaderboard
+   . http://adventofcode.com/2017/stats
+   . http://adventofcode.com/2017/sponsors
+   . http://adventofcode.com/2017/sponsors
+   . https://www.youtube.com/watch?v=cTwZZz0HV8I
+   . http://adventofcode.com/2017
+   . http://adventofcode.com/2017/day/25/input