2024 Day 19 Complete!

2024/day19/main.go

@@ -0,0 +1,98 @@
+package main
+
+import (
+	"fmt"
+	"strings"
+
+	h "git.bullercodeworks.com/brian/adventofcode/helpers"
+)
+
+var cache map[string]int
+
+func main() {
+	inp := h.StdinToStringSlice()
+	cache = make(map[string]int)
+	part1(inp)
+	fmt.Println()
+	part2(inp)
+}
+
+func part1(inp []string) {
+	available, want := parseTowels(inp)
+	fmt.Println("# Part 1")
+	var possible int
+	for i := range want {
+		if build(want[i], available) > 0 {
+			possible++
+		}
+	}
+	fmt.Println("Possible Designs:", possible)
+}
+
+func part2(inp []string) {
+	available, want := parseTowels(inp)
+	fmt.Println("# Part 2")
+	var possible int
+	for i := range want {
+		possible += build(want[i], available)
+	}
+	fmt.Println("Possible Designs:", possible)
+}
+
+func build(towel string, from []string) int {
+	if _, ok := cache[towel]; !ok {
+		if len(towel) == 0 {
+			return 1
+		}
+		res := 0
+		for _, p := range from {
+			if strings.HasPrefix(towel, p) {
+				res += build(towel[len(p):], from)
+			}
+		}
+		cache[towel] = res
+	}
+	return cache[towel]
+}
+
+/* Slow solution...
+func build(towel string, from []string) bool {
+	if len(towel) == 0 {
+		return true
+	}
+
+	for i := range from {
+		if len(from[i]) > len(towel) {
+			continue
+		}
+		var nextFrom bool
+		for j := 0; j < len(from[i]); j++ {
+			if towel[j] != from[i][j] {
+				nextFrom = true
+				break
+			}
+		}
+		// This 'from' didn't match
+		if nextFrom {
+			continue
+		}
+		if build(towel[len(from[i]):], from) {
+			return true
+		}
+	}
+	return false
+}
+*/
+
+func parseTowels(inp []string) ([]string, []string) {
+	var available, want []string
+	pts := strings.Split(inp[0], ", ")
+	for i := range pts {
+		p := strings.TrimSpace(pts[i])
+		available = append(available, p)
+	}
+	for _, n := range inp[2:] {
+		want = append(want, n)
+	}
+	return available, want
+}