tmp

class Solution {
int maxArea = 0;
int row, col;

public:
    int maxAreaOfIsland(vector<vector<int>>& grid) {
        row = grid.size();
        col = grid[0].size();
        for(int i=0; i<row; i++)
            for(int j=0; j<col; j++)
                if(grid[i][j] == 1 && (i*j == 0 || i == row-1 || j == col-1))
                    dfs(i, j, 0, true, grid);

        for(int i=0; i<row; i++)
            for(int j=0; j<col; j++)
                if(grid[i][j] == 1)
                    dfs(i, j, 0, true, grid);
        return maxArea;
    }

    void dfs(int r, int c, int area, bool updateArea, vector<vector<int>> &grid){
        if(r<0 || r >= row || c<0 || c>=col || grid[r][c] == 0) return;
        area++;
        grid[r][c] = 0;
        if(updateArea) maxArea = max(area, maxArea);
        dfs(r+1, c, area, updateArea, grid);
        dfs(r-1, c, area, updateArea, grid);
        dfs(r, c+1, area, updateArea, grid);
        dfs(r, c-1, area, updateArea, grid);
    }
};