2017 Day 05 Complete!

2017/day05/day05.go

@@ -0,0 +1,64 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"log"
+	"os"
+	"strconv"
+)
+
+func main() {
+	inp := StdinToInts()
+	inp2 := make([]int, len(inp))
+	copy(inp2, inp)
+
+	part1(inp)
+	part2(inp2)
+}
+
+func part1(inp []int) {
+	fmt.Println("= Part 1 =")
+	idx, steps := 0, 0
+	for idx >= 0 && idx < len(inp) {
+		jmp := inp[idx]
+		inp[idx] = inp[idx] + 1
+		idx = idx + jmp
+		steps++
+	}
+	fmt.Println("Total Steps:", steps)
+}
+
+func part2(inp []int) {
+	fmt.Println("= Part 2 =")
+	idx, steps := 0, 0
+	for idx >= 0 && idx < len(inp) {
+		jmp := inp[idx]
+		if jmp >= 3 {
+			inp[idx] = inp[idx] - 1
+		} else {
+			inp[idx] = inp[idx] + 1
+		}
+		idx = idx + jmp
+		steps++
+	}
+	fmt.Println("Total Steps:", steps)
+}
+
+func StdinToInts() []int {
+	var input []int
+	scanner := bufio.NewScanner(os.Stdin)
+	for scanner.Scan() {
+		input = append(input, Atoi(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/day05/problem

@@ -0,0 +1,77 @@
+Advent of Code
+
+--- Day 5: A Maze of Twisty Trampolines, All Alike ---
+
+   An urgent interrupt arrives from the CPU: it's trapped in a maze of jump instructions, and it would
+   like assistance from any programs with spare cycles to help find the exit.
+
+   The message includes a list of the offsets for each jump. Jumps are relative: -1 moves to the
+   previous instruction, and 2 skips the next one. Start at the first instruction in the list. The goal
+   is to follow the jumps until one leads outside the list.
+
+   In addition, these instructions are a little strange; after each jump, the offset of that
+   instruction increases by 1. So, if you come across an offset of 3, you would move three instructions
+   forward, but change it to a 4 for the next time it is encountered.
+
+   For example, consider the following list of jump offsets:
+
+ 0
+ 3
+ 0
+ 1
+ -3
+
+   Positive jumps ("forward") move downward; negative jumps move upward. For legibility in this
+   example, these offset values will be written all on one line, with the current instruction marked in
+   parentheses. The following steps would be taken before an exit is found:
+
+     * (0) 3  0  1  -3  - before we have taken any steps.
+     * (1) 3  0  1  -3  - jump with offset 0 (that is, don't jump at all). Fortunately, the instruction
+       is then incremented to 1.
+     *  2 (3) 0  1  -3  - step forward because of the instruction we just modified. The first
+       instruction is incremented again, now to 2.
+     *  2  4  0  1 (-3) - jump all the way to the end; leave a 4 behind.
+     *  2 (4) 0  1  -2  - go back to where we just were; increment -3 to -2.
+     *  2  5  0  1  -2  - jump 4 steps forward, escaping the maze.
+
+   In this example, the exit is reached in 5 steps.
+
+   How many steps does it take to reach the exit?
+
+   Your puzzle answer was _______.
+
+--- Part Two ---
+
+   Now, the jumps are even stranger: after each jump, if the offset was three or more, instead decrease
+   it by 1. Otherwise, increase it by 1 as before.
+
+   Using this rule with the above example, the process now takes 10 steps, and the offset values after
+   finding the exit are left as 2 3 2 3 -1.
+
+   How many steps does it now take to reach the exit?
+
+   Your puzzle answer was _________.
+
+   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.
+
+   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/5/input

2017/day05/testinput

@@ -0,0 +1,5 @@
+0
+3
+0
+1
+-3