class Solution {
public:
    void dfs(vector<vector<char>>& grid, int i, int j, int m, int n) {
        if (i < 0 || i > m - 1 || j < 0 || j > n - 1) {
            return;
        }
        if (grid[i][j] == '0') {
            return;
        }
        grid[i][j] = '0';
        dfs(grid, i - 1, j, m, n);
        dfs(grid, i + 1, j, m, n);
        dfs(grid, i, j - 1, m, n);
        dfs(grid, i, j + 1, m, n);
    }
    int numIslands(vector<vector<char>>& grid) {
        int result = 0;
        int m = grid.size();
        int n= grid[0].size();
        for (int i = 0; i < m; i++) {
            for (int j = 0; j < n; j++) {
                if (grid[i][j] == '1') {
                    result++;
                    dfs(grid, i, j, m, n);
                }
            }
        }
        return result;
    }
};

class Solution {
public:
    void dfs(vector<vector<int>>& grid, int i, int j, int m, int n) {
        if (i < 0 || i > m - 1 || j < 0 || j > n - 1) {
            return;
        }
        if (grid[i][j] == 1) {
            return;
        }
        grid[i][j] = 1;
        dfs(grid, i - 1, j, m, n);
        dfs(grid, i + 1, j, m, n);
        dfs(grid, i, j - 1, m, n);
        dfs(grid, i, j + 1, m, n);
    }
    int closedIsland(vector<vector<int>>& grid) {
        int result = 0;
        int m = grid.size();
        int n = grid[0].size();
        for (int i = 0; i < m; i++) {
            dfs(grid, i, 0, m, n);
            dfs(grid, i, n - 1, m, n);
        }
        for (int i = 0; i < n; i++) {
            dfs(grid, 0, i, m, n);
            dfs(grid, m - 1, i, m, n);
        }
        for (int i = 0; i < m; i++) {
            for (int j = 0; j < n; j++) {
                if (grid[i][j] == 0) {
                    result++;
                    dfs(grid, i, j, m, n);
                }
            }
        }
        return result;
    }
};

class Solution {
public:
    void dfs(vector<vector<int>>& grid, int i, int j, int m, int n) {
        if (i < 0 || i > m - 1 || j < 0 || j > n - 1) {
            return;
        }
        if (grid[i][j] == 0) {
            return;
        }
        grid[i][j] = 0;
        dfs(grid, i - 1, j, m, n);
        dfs(grid, i + 1, j, m, n);
        dfs(grid, i, j - 1, m, n);
        dfs(grid, i, j + 1, m, n);
    }

    int numEnclaves(vector<vector<int>>& grid) {
        int result = 0;
        int m = grid.size();
        int n = grid[0].size();
        for (int i = 0; i < m; i++) {
            dfs(grid, i, 0, m, n);
            dfs(grid, i, n - 1, m, n);
        }
        for (int i = 0; i < n; i++) {
            dfs(grid, 0, i, m, n);
            dfs(grid, m - 1, i, m, n);
        }
        for (int i = 0; i < m; i++) {
            for (int j = 0; j < n; j++) {
                result += (grid[i][j] == 1);
            }
        }
        return result;
    }
};

class Solution {
public:
    int maxArea = 0;
    int dfs(vector<vector<int>>& grid, int i, int j, int m, int n) {
        if (i < 0 || i > m - 1 || j < 0 || j > n - 1) {
            return 0;
        }
        if (grid[i][j] == 0) {
            return 0;
        }
        grid[i][j] = 0;
        return dfs(grid, i - 1, j, m, n) + dfs(grid, i + 1, j, m, n) + dfs(grid, i, j - 1, m, n) + dfs(grid, i, j + 1, m, n) + 1;
    }

    int maxAreaOfIsland(vector<vector<int>>& grid) {
        int m = grid.size();
        int n = grid[0].size();
        for (int i = 0; i < m; i++) {
            for (int j = 0; j < n; j++) {
                if (grid[i][j] == 1) {
                    maxArea = max(maxArea, dfs(grid, i, j, m, n));
                }
            }
        }
        return maxArea;
    }
};

class Solution {
public:
    bool dfs(const vector<vector<int>>& grid1, vector<vector<int>>& grid2, int i, int j, int m, int n) {
        if (i < 0 || i > m - 1 || j < 0 || j > n - 1) {
            return true;
        }
        if (grid2[i][j] == 0) {
            return true;
        }
        if (grid1[i][j] == 0) {
            return false;
        }
        grid2[i][j] = 0;
        bool a = dfs(grid1, grid2, i - 1, j, m, n);
        bool b = dfs(grid1, grid2, i + 1, j, m, n);
        bool c = dfs(grid1, grid2, i, j - 1, m, n);
        bool d = dfs(grid1, grid2, i, j + 1, m, n);
        return a && b && c && d;
    }

    int countSubIslands(vector<vector<int>>& grid1, vector<vector<int>>& grid2) {
        int result = 0;
        int m = grid1.size();
        int n = grid1[0].size();
        for (int i = 0; i < m; i++) {
            for (int j = 0; j < n; j++) {
                if (grid1[i][j] && grid2[i][j]) {
                    result += dfs(grid1, grid2, i, j, m, n);
                }
            }
        }
        return result;
    }
};

int numDistinctIslands(int[][] grid) {

    int m = grid.length, n = grid[0].length;

    // 记录所有岛屿的序列化结果

    HashSet<String> islands = new HashSet<>();

    for (int i = 0; i < m; i++) {

        for (int j = 0; j < n; j++) {

            if (grid[i][j] == 1) {

                // 淹掉这个岛屿，同时存储岛屿的序列化结果

                StringBuilder sb = new StringBuilder();

                // 初始的方向可以随便写，不影响正确性

                dfs(grid, i, j, sb, 666);

                islands.add(sb.toString());

            }

        }

    }

    // 不相同的岛屿数量

    return islands.size();

}