2025 Day 11 Complete!

2025/day11/main.go

@@ -0,0 +1,101 @@
+package main
+
+import (
+	"fmt"
+	"slices"
+	"strings"
+
+	h "git.bullercodeworks.com/brian/adventofcode/helpers"
+)
+
+func main() {
+	inp := h.StdinToStringSlice()
+	part1(inp)
+	fmt.Println()
+	part2(inp)
+}
+
+func part1(inp []string) {
+	m := parseInput(inp)
+	cache = make(map[string]int)
+	fmt.Println("# Part 1")
+	fmt.Println(findPaths("you", "out", m))
+}
+
+func part2(inp []string) {
+	m := parseInput(inp)
+	fmt.Println("# Part 2")
+	fmt.Println(findPaths2(m, m["svr"], false, false, map[track]int{}))
+}
+
+type track struct {
+	node     string
+	fft, dac bool
+}
+
+func parseInput(inp []string) map[string][]string {
+	ret := make(map[string][]string)
+	for i := range inp {
+		pts := strings.Fields(inp[i])
+		st := pts[0][:len(pts[0])-1]
+		ret[st] = pts[1:]
+	}
+	return ret
+}
+
+var cache map[string]int
+
+func findPaths(start, end string, m map[string][]string) int {
+	if v, ok := cache[start]; ok {
+		return v
+	}
+	var ret int
+	v := m[start]
+	for i := range v {
+		if v[i] == end {
+			ret++
+		} else {
+			ret += findPaths(v[i], end, m)
+		}
+	}
+	cache[start] = ret
+	return ret
+}
+
+func findPaths2(m map[string][]string, vals []string, fft, dac bool, cache map[track]int) int {
+	var ret int
+	if slices.Contains(vals, "out") {
+		if fft && dac {
+			return 1
+		}
+		return 0
+	}
+
+	for _, i := range vals {
+		hfft, hdac := fft, dac
+		t := track{
+			node: i,
+			fft:  hfft,
+			dac:  hdac,
+		}
+		if v, ok := cache[t]; ok {
+			ret += v
+			continue
+		}
+
+		switch i {
+		case "fft":
+			hfft = true
+		case "dac":
+			hdac = true
+		}
+		t = track{
+			node: i,
+			fft:  hfft,
+			dac:  hdac,
+		}
+		cache[t] = findPaths2(m, m[i], hfft, hdac, cache)
+		ret += cache[t]
+	}
+	return ret
+}