day 09

2024/09/diskmap.input

@@ -0,0 +1 @@
+2333133121414131402

2024/09/leodev.v

@@ -0,0 +1,111 @@
+import os
+
+fn main() {
+	line := os.read_file('diskmap.input')!
+
+	mut layout := []int{}
+	for i := 0; i < line.len; i += 2 {
+		file_len := line[i] - `0`
+		for _ in 0 .. file_len {
+			layout << (i >> 1)
+		}
+
+		if i + 1 >= line.len {
+			break
+		}
+		gap_len := line[i + 1] - `0`
+		for _ in 0 .. gap_len {
+			layout << -1
+		}
+	}
+
+	print_layout(layout)
+
+	mut l := 0
+	mut r := layout.len - 1
+	mut fragment := layout.clone()
+	for {
+		for fragment[l] != -1 {
+			l++
+		}
+		for fragment[r] == -1 {
+			r--
+		}
+		if l >= r {
+			break
+		}
+		fragment[l] = fragment[r]
+		fragment[r] = -1
+	}
+
+	print_layout(fragment)
+
+	println('part1: ${checksum(fragment)}')
+
+	mut compact := layout.clone()
+	r = compact.len - 1
+	outer: for {
+		for r > 0 && compact[r] == -1 {
+			r--
+		}
+		l = r
+		file_type := compact[r] or { panic('impossible') }
+		for l > 0 && compact[l - 1] == file_type {
+			l--
+		}
+		if l == 0 {
+			break
+		}
+		file_len := r - l + 1
+
+		mut fl := 0
+		for {
+			for fl < compact.len && compact[fl] != -1 {
+				fl++
+			}
+			mut fr := fl
+			for fr < compact.len && compact[fr] == -1 {
+				fr++
+			}
+			if fr > l {
+				r = l - 1
+				continue outer
+			}
+			available := fr - fl
+			if available >= file_len {
+				break
+			}
+			fl = fr
+		}
+
+		for i in 0 .. file_len {
+			compact[fl + i] = compact[r]
+			compact[l + i] = -1
+		}
+	}
+
+	print_layout(compact)
+
+	println('part2: ${checksum(compact)}')
+}
+
+fn print_layout(layout []int) {
+	for value in layout {
+		if value != -1 {
+			print(value)
+		} else {
+			print('.')
+		}
+	}
+	print('\n')
+}
+
+fn checksum(layout []int) i64 {
+	mut total := i64(0)
+	for i, value in layout {
+		if value != -1 {
+			total += value * i
+		}
+	}
+	return total
+}

known/2024/09/leodev.out

@@ -0,0 +1,5 @@
+00...111...2...333.44.5555.6666.777.888899
+0099811188827773336446555566..............
+part1: 1928
+00992111777.44.333....5555.6666.....8888..
+part2: 2858