day 10 part 2

src/main.rs

@@ -19,8 +19,6 @@ fn main() -> Result<()> {
         max_y = std::cmp::max(max_y, y);
         grid.push(cells);
     }
-    // println!("{grid:?}");
-    // println!("{start:?}");
     let mut front = VecDeque::new();
     let mut visited: HashSet<(usize, usize)> = HashSet::new();
     front.push_back((start.0, start.1, 0));
@@ -32,21 +30,48 @@ fn main() -> Result<()> {
             continue;
         }
         visited.insert((x, y));
-        println!("x: {x} y: {y} depth: {depth}");
 
-        if x < max_x && "-J7".contains(grid[y][x + 1]) {
+        let c = grid[y][x];
+
+        if "S-FL".contains(c) && x < max_x && "-J7".contains(grid[y][x + 1]) {
             front.push_back((x + 1, y, depth + 1));
         }
-        if x > 0 && "-LF".contains(grid[y][x - 1]) {
+        if "S-7J".contains(c) && x > 0 && "-LF".contains(grid[y][x - 1]) {
             front.push_back((x - 1, y, depth + 1));
         }
-        if y > 0 && "|7F".contains(grid[y - 1][x]) {
+        if "S|JL".contains(c) && y > 0 && "|7F".contains(grid[y - 1][x]) {
             front.push_back((x, y - 1, depth + 1));
         }
-        if y < max_y && "|JL".contains(grid[y + 1][x]) {
+        if "S|F7".contains(c) && y < max_y && "|JL".contains(grid[y + 1][x]) {
             front.push_back((x, y + 1, depth + 1));
         }
     }
+    let mut enclosed = 0;
+    for j in 0..(max_x + max_y + 2) {
+        println!("j={j}");
+        let mut outside = true;
+        for x in 0..=j {
+            let y = j - x;
+            let Some(row) = grid.get(y) else {
+                continue;
+            };
+            let Some(c) = row.get(x) else {
+                continue;
+            };
+            let o = outside;
+            // in my input, S is equivalent to 7, so outside flips
+            let v = visited.contains(&(x, y));
+            if v {
+                if "-|SL7".contains(*c) {
+                    outside = !outside;
+                }
+            } else if !outside {
+                enclosed += 1;
+            }
+            println!("  {x} {y} visited={v} c={c} outside={o} -> {outside} enclosed={enclosed}",);
+        }
+    }
+    println!("{enclosed}");
     Ok(())
 }