From df30e9abc09f8f61645a96dfb7cbd5a54a1ad012 Mon Sep 17 00:00:00 2001 From: David Ashby Date: Sat, 26 Dec 2020 13:09:37 -0500 Subject: [PATCH] add day 23 --- 23/main.go | 137 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 137 insertions(+) create mode 100644 23/main.go diff --git a/23/main.go b/23/main.go new file mode 100644 index 0000000..9a82c4e --- /dev/null +++ b/23/main.go @@ -0,0 +1,137 @@ +package main + +import ( + "bufio" + "fmt" + "os" + "strconv" + "strings" + "time" +) + +func main() { + start := time.Now() + partOne() + duration := time.Since(start) + partTwo() + duration2 := time.Since(start) + fmt.Printf("p1: %s, p2: %s\n", duration, duration2-duration) +} + +func cupInList(cup int, cups []int) bool { + for _, c := range cups { + if c == cup { + return true + } + } + return false +} + +func generateFullCupset(cups []int, totalCups int) []int { + for i := len(cups); i < totalCups; i = i + 1 { + cups = append(cups, i) + } + return cups +} + +func findTargetCupIndex(cup int, cups []int) int { + for i, c := range cups { + if c == cup { + return i + } + } + return 0 // uh-oh +} + +func step(cups []int) []int { + cupCount := len(cups) + currentCup := cups[0] + removedCups := cups[1:4] + newList := make([]int, 0, cupCount) + newList = append([]int{cups[0]}, cups[4:]...) + var targetCup int + if currentCup == 1 { + targetCup = cupCount + } else { + targetCup = currentCup - 1 + } + for cupInList(targetCup, removedCups) { + targetCup = targetCup - 1 + if targetCup == 0 { + targetCup = cupCount + } + } + tc := findTargetCupIndex(targetCup, newList) + result := make([]int, 0, cupCount) + result = append(result, newList[1:tc+1]...) + result = append(result, removedCups...) + result = append(result, newList[tc+1:]...) + result = append(result, newList[0]) + return result +} + +func runabout(cups []int) string { + oneIndex := findTargetCupIndex(1, cups) + result := "" + for i := oneIndex + 1; i < len(cups); i = i + 1 { + result = result + strconv.Itoa(cups[i]) + } + for i := 0; i < len(cups[:oneIndex]); i = i + 1 { + result = result + strconv.Itoa(cups[i]) + } + return result +} + +func nextTwo(cups []int) (int, int) { + oneIndex := findTargetCupIndex(1, cups) + if oneIndex+1 > len(cups) { + return cups[0], cups[1] + } + if oneIndex+2 > len(cups) { + return cups[len(cups)], cups[0] + } + return cups[oneIndex+1], cups[oneIndex+2] +} + +func partOne() { + f, _ := os.Open("testinput") + reader := bufio.NewReader(f) + scanner := bufio.NewScanner(reader) + + cups := []int{} + + scanner.Scan() + for _, s := range strings.Split(scanner.Text(), "") { + i, _ := strconv.Atoi(s) + cups = append(cups, i) + } + + for i := 0; i < 100; i = i + 1 { + cups = step(cups) + } + + fmt.Println(runabout(cups)) + +} + +func partTwo() { + f, _ := os.Open("testinput") + reader := bufio.NewReader(f) + scanner := bufio.NewScanner(reader) + + cups := []int{} + + scanner.Scan() + for _, s := range strings.Split(scanner.Text(), "") { + i, _ := strconv.Atoi(s) + cups = append(cups, i) + } + + allCups := generateFullCupset(cups, 10000000) + for i := 0; i < 10000000; i = i + 1 { + allCups = step(allCups) + fmt.Println(i) + } + + fmt.Println(nextTwo(allCups)) +}