add day 12

Author: jigfox

.gitignore

@@ -1 +1,2 @@
 /target
+input??

Cargo.lock

@@ -7,4 +7,5 @@ edition = "2021"
 
 [dependencies]
 clap = { version = "4.0.29", features = ["derive"] }
+pathfinding = "4.0.0"
 regex = "1.7.0"

Cargo.toml

@@ -0,0 +1,5 @@
+Sabqponm
+abcryxxl
+accszExk
+acctuvwj
+abdefghi

input12.test

@@ -1,13 +1,69 @@
+use std::convert::identity;
+
 use super::*;
+use pathfinding::prelude::bfs;
+
+#[derive(Clone, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
+struct Pos(usize, usize);
+
+impl Pos {
+    fn successors(&self, map: &Vec<Vec<u8>>) -> Vec<Pos> {
+        let &Pos(x, y) = self;
+        let mut result = Vec::new();
+        let max_target = map[x][y] + 1;
+        if x > 0 && map[x - 1][y] <= max_target {
+            result.push(Pos(x - 1, y));
+        }
+        if x < map.len() - 1 && map[x + 1][y] <= max_target {
+            result.push(Pos(x + 1, y));
+        }
+        if y > 0 && map[x][y - 1] <= max_target {
+            result.push(Pos(x, y - 1));
+        }
+        if y < map[x].len() - 1 && map[x][y + 1] <= max_target {
+            result.push(Pos(x, y + 1));
+        }
+        result
+    }
+}
 
 pub fn solve(filename: String) {
     if let Ok(lines) = read_lines(&filename) {
         // Consumes the iterator, returns an (Optional) String
+        let mut map: Vec<Vec<u8>> = Vec::new();
+        let mut x = 0;
+        let mut target = Pos(0, 0);
+        let mut start = Pos(0, 0);
+        let mut starts: Vec<Pos> = Vec::new();
         for line in lines {
             if let Ok(ip) = line {
-                println!("{}", ip)
+                map.push(ip.chars().map(|c| c as u8).collect());
+                map[map.len() - 1].iter().enumerate().for_each(|(y, c)| {
+                    if *c == ('E' as u8) {
+                        target = Pos(x, y);
+                    }
+                    if *c == ('S' as u8) {
+                        start = Pos(x, y);
+                        starts.push(Pos(x, y));
+                    }
+                    if *c == ('a' as u8) {
+                        starts.push(Pos(x, y));
+                    }
+                });
             }
+            x += 1;
         }
+        let Pos(x, y) = target;
+        map[x][y] = 'z' as u8;
+        let Pos(x, y) = start;
+        map[x][y] = 'a' as u8;
+        let result = bfs(&start, |p| p.successors(&map), |p| *p == target);
+        println!("{:?}", result.expect("").len() - 1);
+        let lens = starts
+            .iter()
+            .map(|s| bfs(s, |p| p.successors(&map), |p| *p == target))
+            .filter_map(identity)
+            .map(|r| r.len() - 1).min();
+        println!("{:?}", lens)
     }
 }
-