Update 1020.飞地的数量.md

problems/1020.飞地的数量.md

@@ -545,6 +545,66 @@ func dfs(grid [][]int, i, j int) {
 }
 ```
 
+bfs:
+
+```go
+var DIRECTIONS = [4][2]int{{-1, 0}, {0, -1}, {1, 0}, {0, 1}}
+var count int = 0
+
+func numEnclaves(grid [][]int) int {
+	rows, cols := len(grid), len(grid[0])
+	// 行
+	for i := range grid[0] {
+		if grid[0][i] == 1 {
+			bfs(grid, 0, i)
+		}
+		if grid[rows-1][i] == 1 {
+			bfs(grid, rows-1, i)
+		}
+	}
+	// 列
+	for j := range grid {
+		if grid[j][0] == 1 {
+			bfs(grid, j, 0)
+		}
+		if grid[j][cols-1] == 1 {
+			bfs(grid, j, cols-1)
+		}
+	}
+	count = 0
+	for i := range grid {
+		for j := range grid[0] {
+			if grid[i][j] == 1 {
+				bfs(grid, i, j)
+			}
+		}
+	}
+	return count
+}
+
+func bfs(grid [][]int, i, j int) {
+	queue := [][]int{}
+	queue = append(queue, []int{i, j})
+	grid[i][j] = 0
+	count++
+	for len(queue) > 0 {
+		cur := queue[0]
+		queue = queue[1:]
+		for _, d := range DIRECTIONS {
+			x, y := cur[0]+d[0], cur[1]+d[1]
+			if x < 0 || x >= len(grid) || y < 0 || y >= len(grid[0]) {
+				continue
+			}
+			if grid[x][y] == 1 {
+				count++
+				queue = append(queue, []int{x, y})
+				grid[x][y] = 0
+			}
+		}
+	}
+}
+```
+
 ### Rust
 
 dfs: