```
void dfs(vector<vector<int>>& M, vector<int>& V, int i) {
for (int j = 0; j < M.size(); j++) {
if (i == j || M[i][j] == 0 || V[j] == 1) continue;
V[j] = 1;
dfs(M, V, j);
}
}
int findCircleNum(vector<vector<int>>& M) {
vector<int> V(M.size(), 0);
int count = 0;
for (int i = 0; i < M.size(); i++) {
if (V[i]) continue;
count++;
dfs(M, V, i);
}
return (count);
}
```