feat: add 2024 day 19 solution

Author: dy-tea

2024/19/dy-tea.v

@@ -0,0 +1,97 @@
+import os
+
+const input_file := towels.input
+
+fn possible(towels []string, current string, query string, mut visited map[string]bool) bool {
+	if current == query {
+		return true
+	}
+
+	if current.len >= query.len {
+		return false
+	}
+
+	if visited[current] {
+		return false
+	}
+
+	visited[current] = true
+
+	for towel in towels {
+		n := current + towel
+
+		if query == n {
+			return true
+		}
+
+		if query.starts_with(n) {
+			if possible(towels, n, query, mut visited) {
+				return true
+			}
+		}
+	}
+
+	return false
+}
+
+fn count_combinations(towels []string, current string, query string, mut visited map[string]u64) u64 {
+	if current == query {
+		return 1
+	}
+
+	if current.len >= query.len {
+		return 0
+	}
+
+	if current in visited {
+		return visited[current]
+	}
+
+	mut sum := u64(0)
+
+	for towel in towels {
+		n := current + towel
+
+		if query.starts_with(n) {
+			sum += count_combinations(towels, n, query, mut visited)
+		}
+	}
+
+	visited[current] = sum
+	return sum
+}
+
+fn p1(input string) ! {
+	lines := os.read_lines(input)!
+
+	towels := lines[0].split(', ')
+	queries := lines[2..]
+
+	mut sum := 0
+	for query in queries {
+		mut visited := map[string]bool{}
+		sum += if possible(towels, '', query, mut visited) { 1 } else { 0 }
+	}
+
+	println(sum)
+}
+
+fn p2(input string) ! {
+	lines := os.read_lines(input)!
+
+	towels := lines[0].split(', ')
+	queries := lines[2..]
+
+	mut sum := u64(0)
+	for query in queries {
+		mut visited := map[string]u64{}
+		sum += count_combinations(towels, '', query, mut visited)
+	}
+
+	println(sum)
+}
+
+fn main() {
+	p1(input_file)!
+	p2(input_file)!
+}

2024/19/towels.input

@@ -0,0 +1,10 @@
+r, wr, b, g, bwu, rb, gb, br
+
+brwrr
+bggr
+gbbr
+rrbgbr
+ubwu
+bwurrg
+brgr
+bbrgwb