Update 0695.岛屿的最大面积.md

problems/0695.岛屿的最大面积.md

@@ -484,6 +484,53 @@ impl Solution {
 }
 ```
 
+bfs:
+
+```rust
+use std::collections::VecDeque;
+impl Solution {
+    const DIRECTIONS: [(i32, i32); 4] = [(0, 1), (1, 0), (-1, 0), (0, -1)];
+
+    pub fn max_area_of_island(grid: Vec<Vec<i32>>) -> i32 {
+        let mut visited = vec![vec![false; grid[0].len()]; grid.len()];
+
+        let mut res = 0;
+        for (i, nums) in grid.iter().enumerate() {
+            for (j, &num) in nums.iter().enumerate() {
+                if !visited[i][j] && num == 1 {
+                    let mut count = 0;
+                    Self::bfs(&grid, &mut visited, (i as i32, j as i32), &mut count);
+                    res = res.max(count);
+                }
+            }
+        }
+
+        res
+    }
+
+    pub fn bfs(grid: &[Vec<i32>], visited: &mut [Vec<bool>], (x, y): (i32, i32), count: &mut i32) {
+        let mut queue = VecDeque::new();
+        queue.push_back((x, y));
+        visited[x as usize][y as usize] = true;
+        *count += 1;
+        while let Some((cur_x, cur_y)) = queue.pop_front() {
+            for (dx, dy) in Self::DIRECTIONS {
+                let (nx, ny) = (cur_x + dx, cur_y + dy);
+                if nx < 0 || nx >= grid.len() as i32 || ny < 0 || ny >= grid[0].len() as i32 {
+                    continue;
+                }
+                let (nx, ny) = (nx as usize, ny as usize);
+                if !visited[nx][ny] && grid[nx][ny] == 1 {
+                    visited[nx][ny] = true;
+                    queue.push_back((nx as i32, ny as i32));
+                    *count += 1;
+                }
+            }
+        }
+    }
+}
+```
+
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