2020 Day 13 Complete!

2020/day13/input

@@ -0,0 +1,2 @@
+1006605
+19,x,x,x,x,x,x,x,x,x,x,x,x,37,x,x,x,x,x,883,x,x,x,x,x,x,x,23,x,x,x,x,13,x,x,x,17,x,x,x,x,x,x,x,x,x,x,x,x,x,797,x,x,x,x,x,x,x,x,x,41,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,29

2020/day13/main.go

@@ -0,0 +1,131 @@
+package main
+
+import (
+	"fmt"
+	"sort"
+	"strings"
+
+	h "git.bullercodeworks.com/brian/adventofcode/helpers"
+)
+
+func main() {
+	fmt.Println("# Day 13")
+	inp := h.StdinToStringSlice()
+	if len(inp) != 2 {
+		fmt.Println("Invalid input")
+		return
+	}
+	part1(inp)
+	part2Rework(inp)
+}
+
+func part1(inp []string) {
+	me := h.Atoi(inp[0])
+	pts := strings.Split(inp[1], ",")
+	earliest := h.MAX_INT
+	var earliestBus int
+	for k := range pts {
+		if pts[k] == "x" {
+			continue
+		}
+		bus := h.Atoi(pts[k])
+		div := me / bus
+		wait := (bus * (div + 1)) - me
+		if earliest > wait {
+			earliest = wait
+			earliestBus = bus
+		}
+	}
+	fmt.Println("## Part 1")
+	fmt.Printf("Answer %d\n\n", earliest*earliestBus)
+}
+
+// This may not work with all inputs...
+func part2Rework(inp []string) {
+	pts := strings.Split(inp[1], ",")
+	buses := make(map[int]int)
+	var keys []int
+	for k, v := range pts {
+		if v == "x" {
+			continue
+		}
+		keys = append(keys, k)
+		buses[k] = h.Atoi(v)
+	}
+	for _, v := range buses {
+		if !h.IsPrime(v) {
+			fmt.Println("Not all buses are prime numbers... This solution _may not work_. Or it may still.", h.SHRUG)
+			break
+		}
+	}
+	res := 0
+	mins := buses[keys[0]]
+	for k := 1; k < len(keys); k++ {
+		wrk := keys[k]
+		bus := buses[wrk]
+		for (res+wrk)%bus != 0 {
+			res = res + mins
+		}
+		mins = mins * bus
+	}
+	fmt.Println("## Part 2")
+	fmt.Printf("Answer: %d\n", res)
+}
+
+/*
+           7      13      59      31      19
+1068781    D       .       .       .       .
+1068782    .       D       .       .       .
+1068783    .       .       .       .       .
+1068784    .       .       .       .       .
+1068785    .       .       D       .       .
+1068786    .       .       .       .       .
+1068787    .       .       .       D       .
+1068788    D       .       .       .       D
+
+7  = 0
+13 = 1
+59 = 4
+31 = 6
+19 = 7
+
+*/
+
+// I think this will get there... Eventually... Maybe...
+func part2(inp []string) {
+	pts := strings.Split(inp[1], ",")
+	wrk := make(map[int]int)
+	var keys []int
+	var vals []int
+	var highK, highV int
+	for k := range pts {
+		if pts[k] == "x" {
+			continue
+		}
+		keys = append(keys, k)
+		vals = append(vals, wrk[k])
+		wrk[k] = h.Atoi(pts[k])
+		if wrk[k] > highV {
+			highK = k
+			highV = wrk[k]
+		}
+	}
+	sort.Sort(sort.Reverse(sort.IntSlice(keys)))
+	sort.Sort(sort.Reverse(sort.IntSlice(keys)))
+	target := highV - highK
+	for !checkMap(target, keys, wrk) {
+		target = target + highV
+	}
+
+	fmt.Println("## Part 2")
+	fmt.Printf("Answer: %d\n", target)
+}
+
+func checkMap(target int, keys []int, all map[int]int) bool {
+	for _, k := range keys {
+		if (target+k)%all[k] != 0 {
+			return false
+		}
+	}
+	return true
+}

2020/day13/testinput

@@ -0,0 +1,2 @@
+939
+7,13,x,x,59,x,31,19

2020/day13/testinput2

@@ -0,0 +1,2 @@
+1
+1789,37,47,1889

go.mod

@@ -3,20 +3,13 @@ module git.bullercodeworks.com/brian/adventofcode
 go 1.13
 
 require (
-	github.com/BurntSushi/toml v0.3.1 // indirect
 	github.com/br0xen/termbox-screen v0.0.0-20190712162752-c91f70ac38c6
 	github.com/br0xen/termbox-util v0.0.0-20190325151025-c168c0df31ca
-	github.com/br0xen/user-config v0.0.0-20170914134719-16e743ec93a2 // indirect
-	github.com/casimir/xdg-go v0.0.0-20160329195404-372ccc2180da // indirect
 	github.com/fatih/color v1.7.0
 	github.com/go-gl/gl v0.0.0-20190320180904-bf2b1f2f34d7
 	github.com/go-gl/glfw v0.0.0-20191125211704-12ad95a8df72
-	github.com/google/uuid v1.1.1 // indirect
-	github.com/jcelliott/lumber v0.0.0-20160324203708-dd349441af25 // indirect
 	github.com/mattn/go-colorable v0.1.4 // indirect
 	github.com/mattn/go-isatty v0.0.10 // indirect
 	github.com/mattn/go-runewidth v0.0.7 // indirect
-	github.com/nanobox-io/golang-scribble v0.0.0-20190309225732-aa3e7c118975 // indirect
-	github.com/nlopes/slack v0.6.0 // indirect
 	github.com/nsf/termbox-go v0.0.0-20190817171036-93860e161317
 )

helpers/helpers.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"io/ioutil"
 	"log"
+	"math"
 	"os"
 	"strconv"
 	"strings"
@@ -25,9 +26,11 @@ const (
 
 	MAX_INT = int(^uint(0) >> 1)
 	MIN_INT = -MAX_INT - 1
+
+	SHRUG = "¯\\_(ツ)_/¯"
 )
 
-// Find the greatest common denominator
+// Gcd Finds the greatest common denominator
 func Gcd(x, y int) int {
 	for y != 0 {
 		x, y = y, x%y
@@ -35,7 +38,7 @@ func Gcd(x, y int) int {
 	return x
 }
 
-// Find the least common multiple, using gcd
+// Lcm finds the least common multiple, using gcd
 func Lcm(a, b int, integers ...int) int {
 	result := a * b / Gcd(a, b)
 	for i := 0; i < len(integers); i++ {
@@ -44,6 +47,7 @@ func Lcm(a, b int, integers ...int) int {
 	return result
 }
 
+// AbsInt returns the absolute value of i
 func AbsInt(i int) int {
 	if i < 0 {
 		return i * -1
@@ -51,6 +55,7 @@ func AbsInt(i int) int {
 	return i
 }
 
+// ArgIsSet return true if an argument with the asked for key is present
 func ArgIsSet(a string) bool {
 	for i := range os.Args {
 		if os.Args[i] == a || strings.HasPrefix(os.Args[i], a+"=") {
@@ -60,6 +65,7 @@ func ArgIsSet(a string) bool {
 	return false
 }
 
+// GetArgValue returns the argument with the asked for key or ""
 func GetArgValue(a string) string {
 	for i := range os.Args {
 		if strings.HasPrefix(os.Args[i], a+"=") {
@@ -69,6 +75,7 @@ func GetArgValue(a string) string {
 	return ""
 }
 
+// GetArgNumber returns the asked for argument position or ""
 func GetArgNumber(i int) string {
 	if len(os.Args) > i {
 		return os.Args[i]
@@ -76,6 +83,7 @@ func GetArgNumber(i int) string {
 	return ""
 }
 
+// OptArgNumber returns either the asked for argument position or the passed default
 func OptArgNumber(i int, def string) string {
 	if len(os.Args) > i {
 		return os.Args[i]
@@ -83,6 +91,7 @@ func OptArgNumber(i int, def string) string {
 	return def
 }
 
+// StdinToIntSlice reads from stdin and returns it as an int slice
 func StdinToIntSlice() []int {
 	var ret []int
 	st := StdinToStringSlice()
@@ -92,6 +101,7 @@ func StdinToIntSlice() []int {
 	return ret
 }
 
+// StdinToStringSlice reads from stdin and returns it as a string slice
 func StdinToStringSlice() []string {
 	var input []string
 	scanner := bufio.NewScanner(os.Stdin)
@@ -101,10 +111,12 @@ func StdinToStringSlice() []string {
 	return input
 }
 
+// StdinToCoordMap reads stdin and returns it as a CoordByteMap
 func StdinToCoordMap() CoordByteMap {
 	return StringSliceToCoordByteMap(StdinToStringSlice())
 }
 
+// Atoi is basically redundant
 func Atoi(i string) int {
 	var ret int
 	var err error
@@ -114,10 +126,12 @@ func Atoi(i string) int {
 	return ret
 }
 
+// Itoa is basically redundant
 func Itoa(i int) string {
 	return strconv.Itoa(i)
 }
 
+// StdinToString reads from stdin and returns a string
 func StdinToString() string {
 	var input string
 	scanner := bufio.NewScanner(os.Stdin)
@@ -127,14 +141,17 @@ func StdinToString() string {
 	return input
 }
 
+// FileToStringSlice takes a file and returns it as a slice of strings
 func FileToStringSlice(fn string) []string {
 	return strings.Split(string(FileToBytes(fn)), "\n")
 }
 
+// FileToString reads a file and returns it as a string
 func FileToString(fn string) string {
 	return string(FileToBytes(fn))
 }
 
+// FileToBytes reads a file and returns it as a slice of bytes
 func FileToBytes(fn string) []byte {
 	var c []byte
 	var err error
@@ -146,6 +163,7 @@ func FileToBytes(fn string) []byte {
 	return c
 }
 
+// PrintProgress is for outputting a progress bar
 func PrintProgress(curr, total int) {
 	pct := int(float64(curr)/float64(total)) * 100
 	for i := 0; i < 100; i += 10 {
@@ -155,6 +173,7 @@ func PrintProgress(curr, total int) {
 	}
 }
 
+// StringPermutations takes a string and returns all permutations of it
 func StringPermutations(str string) []string {
 	perms := stringPermHelper(str, 0)
 	var wrk []string
@@ -186,6 +205,7 @@ func stringPermHelper(str string, i int) []string {
 	return ret
 }
 
+// IntPermutations takes a slice of ints and returns all permutations of it
 func IntPermutations(inp []int) [][]int {
 	perms := intPermHelper(inp, 0)
 	var wrk [][]int
@@ -219,6 +239,7 @@ func intPermHelper(inp []int, i int) [][]int {
 	return ret
 }
 
+// IntSlicesAreEqual takes two int slices and returns if they are equal
 func IntSlicesAreEqual(s1 []int, s2 []int) bool {
 	if len(s1) != len(s2) {
 		return false
@@ -231,6 +252,8 @@ func IntSlicesAreEqual(s1 []int, s2 []int) bool {
 	return true
 }
 
+// StringSliceContains takes a string slice and a string and return true
+// if the string is in the slice
 func StringSliceContains(h []string, n string) bool {
 	for _, v := range h {
 		if v == n {
@@ -239,3 +262,13 @@ func StringSliceContains(h []string, n string) bool {
 	}
 	return false
 }
+
+// IsPrime takes a number and return true if that number is prime
+func IsPrime(value int) bool {
+	for i := 2; i <= int(math.Floor(float64(value)/2)); i++ {
+		if value%i == 0 {
+			return false
+		}
+	}
+	return value > 1
+}