岛屿数量

class Solution {
private:
    void numIslandsCore(vector<vector<char>>& tmpGrid,int i,int j,int row,int col)
    {
        if(i<0||i>=row||j<0||j>=col||tmpGrid[i][j]!=‘1‘)
            return ;
        
        tmpGrid[i][j]=‘2‘;
        numIslandsCore(tmpGrid,i+1,j,row,col);
        numIslandsCore(tmpGrid,i-1,j,row,col);
        numIslandsCore(tmpGrid,i,j+1,row,col);
        numIslandsCore(tmpGrid,i,j-1,row,col);
    }
public:
    int numIslands(vector<vector<char>>& grid) {
        if(grid.empty()||grid[0].empty())
            return 0;

        vector<vector<char>> tmpGrid(grid);
        int row=tmpGrid.size();
        int col=tmpGrid[0].size();
        int res=0;
        for(int i=0;i<row;++i)
        {
            for(int j=0;j<col;++j)
            {
                if(tmpGrid[i][j]==‘1‘)
                {
                    ++res;
                    numIslandsCore(tmpGrid,i,j,row,col);
                }
            }
        }
        return res;
    }
};