leetcode.547https://leetcode-cn.com/problems/number-of-provinces/

class Solution {
public:
    int findCircleNum(vector<vector<int>>& isConnected) {
        function<void(int)> dfs = [&](int x) -> void {
            isConnected[x][x] = 0;
            for (int i = 0; i < isConnected.size(); i++) {
                if (isConnected[x][i] == 1 && isConnected[i][i] == 1) {
                    dfs(i);
                }
            }
        };
        int ans = 0;
        for (int i = 0; i < isConnected.size(); i++) {
            if (isConnected[i][i] == 1) {
                dfs(i);
                ans++;
            }
        }
        return ans;
    }
};