题解 | 岛屿数量

class Solution {
public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 判断岛屿数量
     * @param grid char字符型vector<vector<>> 
     * @return int整型
     */
    int dx[4] = {-1, 0, 1, 0}, dy[4] = {0, 1, 0, -1};

    int solve(vector<vector<char> >& grid) {
        int cnt = 0;
        for (int i = 0; i < grid.size(); i++) {
            for (int j = 0; j < grid[i].size(); j++) {
                if (grid[i][j] == '1') {
                    cnt++;
                    dfs(grid, i, j);
                }
            }
        }
        return cnt;
    }

    void dfs(vector<vector<char>>& grid, int x, int y) {
        grid[x][y] = '0';
        for (int i = 0; i < 4; i++) {
            int a = x + dx[i], b = y + dy[i];
            if (a >= 0 && a < grid.size() && b >= 0 && b < grid[0].size() && grid[a][b] == '1') {
                dfs(grid, a, b);
            }
        }
    }
};