class Solution {
public:
    int FindRoot(vector<int>& bing, int idx) {
        if (bing[idx] == -1) return idx;
        else return FindRoot(bing, bing[idx]);
    }
    int findCircleNum(vector<vector<int>>& isConnected) {
        int len = isConnected.size();
        if (!len) return 0;
        vector<int> bing(len, -1);
        for (int i = 0; i < len; i++) {
            for (int j = 0; j < len; j++) {
                if (i == j || isConnected[i][j] == 0)
                    continue;
                int acsi = FindRoot(bing, i);
                int acsj = FindRoot(bing, j);
                if (acsi != acsj) {
                    bing[acsi] = acsj;
                }
            }   
        }
        int ret = 0;
        for (int i = 0; i < len; i++) {
            if (bing[i] == -1) ret++;
            else continue;
        }
        return ret;
    }
};