126 lines
2.8 KiB
Go
126 lines
2.8 KiB
Go
package day21
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import (
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"strconv"
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"strings"
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)
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type coordinate struct {
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row, col int
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}
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var numberPad = map[string]coordinate{
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"7": {0, 0}, "8": {0, 1}, "9": {0, 2},
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"4": {1, 0}, "5": {1, 1}, "6": {1, 2},
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"1": {2, 0}, "2": {2, 1}, "3": {2, 2},
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"0": {3, 1}, "A": {3, 2},
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}
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var robotPad = map[string]coordinate{
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"^": {0, 1}, "A": {0, 2},
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"<": {1, 0}, "v": {1, 1}, ">": {1, 2},
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}
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type cacheKey struct {
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sequence string
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iterations int
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}
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var memo = make(map[cacheKey]int)
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func Part1(input string) int {
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codes := parseInput(input)
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numpadGraph := createGraph(numberPad, coordinate{3, 0})
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dirpadGraph := createGraph(robotPad, coordinate{0, 0})
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total := 0
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for _, code := range codes {
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codeInt, _ := strconv.Atoi(code[:len(code)-1])
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total += codeInt * getLength(code, 3, true, numpadGraph, dirpadGraph)
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}
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return total
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}
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func Part2(input string) int {
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codes := parseInput(input)
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numpadGraph := createGraph(numberPad, coordinate{3, 0})
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dirpadGraph := createGraph(robotPad, coordinate{0, 0})
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total := 0
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for _, code := range codes {
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codeInt, _ := strconv.Atoi(code[:len(code)-1])
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total += codeInt * getLength(code, 26, true, numpadGraph, dirpadGraph)
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}
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return total
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}
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func parseInput(input string) []string {
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parts := strings.Split(input, "\n")
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codes := []string{}
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codes = append(codes, parts...)
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return codes
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}
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func createGraph(keypad map[string]coordinate, invalidCoords coordinate) map[string]string {
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graph := make(map[string]string)
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for a, coordA := range keypad {
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for b, coordB := range keypad {
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x1, y1 := coordA.row, coordA.col
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x2, y2 := coordB.row, coordB.col
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path := strings.Repeat("<", max(0, y1-y2)) +
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strings.Repeat("v", max(0, x2-x1)) +
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strings.Repeat("^", max(0, x1-x2)) +
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strings.Repeat(">", max(0, y2-y1))
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if invalidCoords == (coordinate{x1, y2}) || invalidCoords == (coordinate{x2, y1}) {
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path = reverseString(path)
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}
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graph[a+"->"+b] = path + "A"
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}
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}
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return graph
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}
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func reverseString(s string) string {
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runes := []rune(s)
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for i, j := 0, len(runes)-1; i < j; i, j = i+1, j-1 {
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runes[i], runes[j] = runes[j], runes[i]
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}
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return string(runes)
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}
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func getLength(sequence string, iterations int, firstIter bool, numpadGraph map[string]string, dirpadGraph map[string]string) int {
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if iterations == 0 {
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return len(sequence)
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}
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key := cacheKey{sequence: sequence, iterations: iterations}
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if cachedResult, exists := memo[key]; exists {
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return cachedResult
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}
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graph := numpadGraph
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if !firstIter {
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graph = dirpadGraph
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}
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totalLength := 0
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prev := "A"
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for _, char := range sequence {
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graphKey := prev + "->" + string(char)
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if subSequence, exists := graph[graphKey]; exists {
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totalLength += getLength(subSequence, iterations-1, false, numpadGraph, dirpadGraph)
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}
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prev = string(char)
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}
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memo[key] = totalLength
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return totalLength
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}
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