day 10

2024/10/leodev.v

@@ -0,0 +1,73 @@
+import os
+
+fn main() {
+	lines := os.read_lines('map.input')!
+
+	mut trailheads := [][2]int{}
+	for y, line in lines {
+		for x, c in line {
+			if c == `0` {
+				trailheads << [y, x]!
+			}
+		}
+	}
+
+	mut state := State{
+		lines: lines
+	}
+
+	mut total1 := 0
+	mut total2 := 0
+	for th in trailheads {
+		total1 += state.traverse(th[0], th[1])
+		total2 += state.part2()
+	}
+
+	println('part1: ${total1}')
+	println('part2: ${total2}')
+}
+
+struct State {
+	lines []string
+mut:
+	trailends map[string]int
+}
+
+fn (mut s State) traverse(y int, x int) int {
+	s.trailends = map[string]int{}
+	s.t(y, x, `0`)
+	return s.trailends.len
+}
+
+fn (s State) part2() int {
+	mut total := 0
+	for _, v in s.trailends {
+		total += v
+	}
+	return total
+}
+
+const offsets = [
+	[0, 1]!,
+	[1, 0]!,
+	[0, -1]!,
+	[-1, 0]!,
+]
+
+fn (mut s State) t(y int, x int, current u8) {
+	for off in offsets {
+		ny := y + off[0]
+		nx := x + off[1]
+		if ny < 0 || ny >= s.lines.len || nx < 0 || nx >= s.lines[0].len {
+			continue
+		}
+		if s.lines[ny][nx] != current + 1 {
+			continue
+		}
+		if current == `8` {
+			s.trailends['${ny},${nx}']++
+			continue
+		}
+		s.t(ny, nx, s.lines[ny][nx])
+	}
+}

2024/10/map.input

@@ -0,0 +1,8 @@
+89010123
+78121874
+87430965
+96549874
+45678903
+32019012
+01329801
+10456732

known/2024/10/leodev.out

@@ -0,0 +1,2 @@
+part1: 36
+part2: 81