题目要求

思路
1.使用广度优先遍历，将数组中所有为1的元素遍历一遍，遍历过程中使用递归，讲该元素的上下左右四个方向的元素值也置为0
2.统计一共执行过多少次，次数就是岛屿数量
代码实现

class Solution {
public:
    int solve(vector<vector<char> >& grid) {
        int n = grid.size();
        int m = grid[0].size();
        int index = 0;
        for(int i = 0; i < n; i++)
        {
            for(int j = 0; j < m; j++)
            {
                if(grid[i][j] == '1')
                {
                    index++;
                    // cout << i << " " << j <<endl;
                    dfs(grid, i, j);
                }
            }
        }
        return index;
    }

    void dfs(vector<vector<char>>& grid, int i, int j)
    {
        if(grid[i][j] == '1')
            grid[i][j] = '0';

        if(i > 0 && grid[i-1][j] == '1')
            dfs(grid, i-1, j);
        if(j > 0 && grid[i][j-1] == '1')
            dfs(grid, i, j-1);
        if(i < grid.size() - 1 && grid[i+1][j] == '1')
            dfs(grid, i+1, j);
        if(j < grid[0].size() - 1 && grid[i][j+1] == '1')
            dfs(grid, i, j+1);
    }
};