day11-12

aoc_2024/src/day11.rs

@@ -1,13 +1,10 @@
-use std::collections::VecDeque;
-
 use aoc_runner_derive::{aoc, aoc_generator};
-use hashbrown::{hash_map::Entry, HashMap};
+use hashbrown::HashMap;
 use nom::{
     character::complete::{space1, u64 as parse_usize},
     error::Error,
     multi::separated_list1,
 };
-use rayon::prelude::*;
 
 type Input = Vec<usize>;
 

aoc_2024/src/day12.rs

@@ -0,0 +1,174 @@
+use aoc_runner_derive::{aoc, aoc_generator};
+
+type Input = Vec<Vec<char>>;
+
+#[aoc_generator(day12)]
+fn parse(input: &str) -> Input {
+    input.lines().map(|line| line.chars().collect()).collect()
+}
+
+#[aoc(day12, part1)]
+fn part1(input: &Input) -> usize {
+    let w = input[0].len();
+    let h = input.len();
+
+    let mut region_idx = -1;
+    let mut region_border_size = vec![];
+    let mut region_size = vec![];
+    let mut region = vec![vec![-1; w]; h];
+
+    for y in 0..h {
+        for x in 0..w {
+            let val = input[y][x];
+            if region[y][x] == -1 {
+                region_idx += 1;
+                let mut queue = vec![(x, y)];
+                let mut size = 0;
+                let mut border_size = 0;
+
+                while let Some((x, y)) = queue.pop() {
+                    if region[y][x] != -1 {
+                        continue;
+                    }
+
+                    region[y][x] = region_idx;
+                    size += 1;
+
+                    let mut sides = 4;
+
+                    if x > 0 && input[y][x - 1] == val {
+                        queue.push((x - 1, y));
+                        sides -= 1;
+                    }
+                    if x < w - 1 && input[y][x + 1] == val {
+                        queue.push((x + 1, y));
+                        sides -= 1;
+                    }
+                    if y > 0 && input[y - 1][x] == val {
+                        queue.push((x, y - 1));
+                        sides -= 1;
+                    }
+                    if y < h - 1 && input[y + 1][x] == val {
+                        queue.push((x, y + 1));
+                        sides -= 1;
+                    }
+
+                    border_size += sides;
+                }
+
+                region_size.push(size);
+                region_border_size.push(border_size);
+            }
+        }
+    }
+
+    region_size
+        .iter()
+        .zip(region_border_size.iter())
+        .map(|(a, b)| *a * *b)
+        .sum()
+}
+
+#[aoc(day12, part2)]
+fn part2(input: &Input) -> usize {
+    let w = input[0].len();
+    let h = input.len();
+
+    let mut region_idx = -1;
+    let mut region_border_size = vec![];
+    let mut region_size = vec![];
+    let mut region = vec![vec![-1; w]; h];
+
+    for y in 0..h {
+        for x in 0..w {
+            let val = input[y][x];
+            if region[y][x] == -1 {
+                region_idx += 1;
+                let mut queue = vec![(x, y)];
+                let mut size = 0;
+                let mut border_size = 0;
+
+                while let Some((x, y)) = queue.pop() {
+                    if region[y][x] != -1 {
+                        continue;
+                    }
+
+                    region[y][x] = region_idx;
+                    size += 1;
+
+                    let mut up = false;
+                    let mut down = false;
+                    let mut left = false;
+                    let mut right = false;
+                    let mut up_right = false;
+                    let mut down_left = false;
+
+                    if x > 0 && input[y][x - 1] == val {
+                        queue.push((x - 1, y));
+                        left = true;
+                    }
+                    if x < w - 1 && input[y][x + 1] == val {
+                        queue.push((x + 1, y));
+                        right = true;
+                    }
+                    if y > 0 && input[y - 1][x] == val {
+                        queue.push((x, y - 1));
+                        up = true;
+                    }
+                    if y < h - 1 && input[y + 1][x] == val {
+                        queue.push((x, y + 1));
+                        down = true;
+                    }
+                    if y > 0 && x < w - 1 && input[y - 1][x + 1] == val {
+                        up_right = true;
+                    }
+                    if y < h - 1 && x > 0 && input[y + 1][x - 1] == val {
+                        down_left = true;
+                    }
+
+                    if !up && !left {
+                        border_size += 2;
+                    }
+                    if !down && !right {
+                        border_size += 2;
+                    }
+                    if up && right && !up_right {
+                        border_size += 2;
+                    }
+                    if down && left && !down_left {
+                        border_size += 2;
+                    }
+                }
+
+                region_size.push(size);
+                region_border_size.push(border_size);
+            }
+        }
+    }
+
+    region_size
+        .iter()
+        .zip(region_border_size.iter())
+        .map(|(a, b)| *a * *b)
+        .sum()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn part1_example() {
+        assert_eq!(part1(&parse("AAAA\nBBCD\nBBCC\nEEEC")), 140);
+        assert_eq!(part1(&parse("OOOOO\nOXOXO\nOOOOO\nOXOXO\nOOOOO")), 772);
+        assert_eq!(part1(&parse("RRRRIICCFF\nRRRRIICCCF\nVVRRRCCFFF\nVVRCCCJFFF\nVVVVCJJCFE\nVVIVCCJJEE\nVVIIICJJEE\nMIIIIIJJEE\nMIIISIJEEE\nMMMISSJEEE")), 1930);
+    }
+
+    #[test]
+    fn part2_example() {
+        assert_eq!(part2(&parse("AAAA\nBBCD\nBBCC\nEEEC")), 80);
+        assert_eq!(part2(&parse("OOO\nOXO\nOOO")), 68);
+        assert_eq!(part2(&parse("OOOOO\nOXXXX\nOOOOO\nOXXXX\nOOOOO")), 236);
+        assert_eq!(part2(&parse("RRRRIICCFF\nRRRRIICCCF\nVVRRRCCFFF\nVVRCCCJFFF\nVVVVCJJCFE\nVVIVCCJJEE\nVVIIICJJEE\nMIIIIIJJEE\nMIIISIJEEE\nMMMISSJEEE")), 1206);
+    }
+}

aoc_2024/src/lib.rs

@@ -1,6 +1,7 @@
 mod day1;
 mod day10;
 mod day11;
+mod day12;
 mod day2;
 mod day3;
 mod day4;