Day 12

input/12.txt

@@ -0,0 +1,41 @@
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+abaaaaaccccccccccccccccccccaaaaaaaaaacccaaaaaaacccccaaccccccccccccccccccccccccccccccccccccaaacccccccccccaacaaaccccccccciiinntttxxxxxxxyyvvvvvqqqqljjcccccc
+abccaaaccaccccccccaaacccccccaaaaaaaaaccccaaaaaacccccccccccccccccccccccccccccccaacccccccaaaaacaaccccccccccccaacccccccccchhinnnttxxxxxxyyyyyvvvvqqqjjjcccccc
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+abccccaaaacccccccaaaaaaccccccaaaaaacccccaaaaaaaaaacccccccccccccccccccaaccccccaaaaccccccccaaaaacccccccccccccccccccccccccchhhnntttxxxyyyyyyyvvvvqqqjjjcccccc
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+abcccaaaaaacccccccaaaaacccccaaacaaacaaaaaaaaaaccccccccccccaaacccccaaaaaaaaccccccccccccccaacaaacccccccaacaaacccccccccccchhhmmmtswwwyyyyyyvvvqqqqjjjjdddcccc
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+abaccccccccaaaaaaaccaaacccccccccccccccccaaaccccccccaaacaaaaaccccccaaacccccccccccccaaaacccccccccccccccccccaaaaaccccccccccccccccccaffffffkkkeeeeeccaaccccccc
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+abaacccccccccaaccccccccccccccccaaccccccaaaaacaaccaacccaaaaacaaaaaaaaacccccccccaaaaaaaaccccccaaacaacccccccccaacccccccccccccccccccccaaaccceaecccccccccccccaa
+abaacccccccccccccccccccccccccccaaaaaacccaaaaaaaaaaaccaaacaaccaaaaaaaaaaaaacccccaaaaaaacccccccaaaaaccccccccccccccccccccccccccccccccaaacccccccccccccccaaacaa
+abcccccccccccccccccccccccccccccaaaaaccccaacaacaaaaacccaaccccccaaaaaaaaaaaacccccaaaaacccccccccaaaaaaaccccccccccccccccccccccccccccccaaacccccccccccccccaaaaaa
+abcccccccccccccccccccccccccccaaaaaaaccccccccaaaaaaaaccccccccccaaaaaaaaaaccccccaaaaaaccccccccaaaaaaaaccccccccccccccccccccccccccccccccccccccccccccccccaaaaaa

src/day12/mod.rs

@@ -1,20 +1,137 @@
 use crate::read;
 use itertools::Itertools;
 
-//#[derive(Debug, PartialEq, Eq, Clone, Hash)]
+#[derive(Debug, PartialEq, Eq, Clone, Hash, Default)]
+struct Coord {
+    pub row: i32,
+    pub col: i32,
+}
 
 pub fn run() {
     let input = read("12");
     let lines = input.lines();
-    let lines = input.split("\n\n");
+    let mut start: Coord = Default::default();
+    let mut target: Coord = Default::default();
+    let map = lines
+        .enumerate()
+        .map(|(r, l)| {
+            l.chars()
+                .enumerate()
+                .map(|(col, c)| match c {
+                    'S' => {
+                        start = Coord {
+                            row: r as i32,
+                            col: col as i32,
+                        };
+                        0
+                    }
+                    'E' => {
+                        target = Coord {
+                            row: r as i32,
+                            col: col as i32,
+                        };
+                        25
+                    }
+                    c => (c as u32) - ('a' as u32),
+                })
+                .collect_vec()
+        })
+        .collect_vec();
 
     #[cfg(feature = "part1")]
     {
-        println!("Day 12, Part 01: {}", "TODO");
+        println!("Day 12, Part 01: {:?}", bfs(&map, start, target.clone()));
     }
 
     #[cfg(feature = "part2")]
     {
-        println!("Day 12, Part 02: {}", "TODO");
+        let starting_points = map
+            .iter()
+            .enumerate()
+            .flat_map(|(row, v)| {
+                v.iter()
+                    .enumerate()
+                    .filter(|(_, vv)| **vv == 0)
+                    .map(|(col, _)| Coord {
+                        row: row as i32,
+                        col: col as i32,
+                    })
+                    .collect_vec()
+            })
+            .collect_vec();
+        let min = starting_points
+            .iter()
+            .filter_map(|start| bfs(&map, start.clone(), target.clone()))
+            .min();
+        println!("Day 12, Part 02: {:?}", min);
     }
 }
+
+fn bfs(map: &Vec<Vec<u32>>, start: Coord, target: Coord) -> Option<usize> {
+    let mut visited = vec![vec![false; map[0].len()]; map.len()];
+    let mut queue = std::collections::VecDeque::new();
+    queue.push_back((start, 0));
+
+    while let Some((next, path_length)) = queue.pop_front() {
+        if next == target {
+            return Some(path_length);
+        }
+        let up = Coord {
+            row: next.row - 1,
+            col: next.col,
+        };
+        let down = Coord {
+            row: next.row + 1,
+            col: next.col,
+        };
+        let left = Coord {
+            row: next.row,
+            col: next.col - 1,
+        };
+        let right = Coord {
+            row: next.row,
+            col: next.col + 1,
+        };
+        let can_down = check_bounds(&down, map)
+            && !visited[down.row as usize][down.col as usize]
+            && map[next.row as usize][next.col as usize] + 1
+                >= map[down.row as usize][down.col as usize];
+        if can_down {
+            visited[down.row as usize][down.col as usize] = true;
+            queue.push_back((down, path_length + 1));
+        }
+        let can_up = check_bounds(&up, map)
+            && !visited[up.row as usize][up.col as usize]
+            && map[next.row as usize][next.col as usize] + 1
+                >= map[up.row as usize][up.col as usize];
+        if can_up {
+            visited[up.row as usize][up.col as usize] = true;
+            queue.push_back((up, path_length + 1));
+        }
+        let can_left = check_bounds(&left, map)
+            && !visited[left.row as usize][left.col as usize]
+            && map[next.row as usize][next.col as usize] + 1
+                >= map[left.row as usize][left.col as usize];
+        if can_left {
+            visited[left.row as usize][left.col as usize] = true;
+            queue.push_back((left, path_length + 1));
+        }
+        let can_right = check_bounds(&right, map)
+            && !visited[right.row as usize][right.col as usize]
+            && map[next.row as usize][next.col as usize] + 1
+                >= map[right.row as usize][right.col as usize];
+        if can_right {
+            visited[right.row as usize][right.col as usize] = true;
+            queue.push_back((right, path_length + 1));
+        }
+    }
+    None
+}
+
+fn check_bounds(coord: &Coord, map: &Vec<Vec<u32>>) -> bool {
+    coord.row >= 0
+        && coord.col >= 0
+        && coord.row < map.len() as i32
+        && coord.row < map.len() as i32
+        && coord.col < map[coord.row as usize].len() as i32
+}