1020. 飞地的数量

C代码：DFS

void dfs (int** grid, int x, int y, int m, int n) {
    if (x < 0 || x >= m || y < 0 || y >= n || grid[x][y] == 0) {
        return;
    }
    grid[x][y] = 0;
    dfs(grid, x + 1, y, m, n);
    dfs(grid, x - 1, y, m, n);
    dfs(grid, x, y + 1, m, n);
    dfs(grid, x, y - 1, m, n);
}

int numEnclaves(int** grid, int gridSize, int* gridColSize){
    int m = gridSize;
    int n = gridColSize[0];
    for (int i = 0; i < m; ++i) {
        dfs(grid, i, 0, m, n);
        dfs(grid, i, n - 1, m, n);
    }
    for (int j = 1; j < n - 1; ++j) {
        dfs(grid, 0, j, m, n);
        dfs(grid, m - 1, j, m, n);
    }

    int cnt = 0;
    for (int i = 0; i < m; ++i) {
        for (int j = 0; j < n; ++j) {
            if (grid[i][j] == 1) {
                ++cnt;
            }
        }
    }
    return cnt;
}