【CF913B】Christmas Spruce

【CF913B】Christmas Spruce

链接

传送门

代码

#include <iostream>
#include <algorithm>using namespace std;
const int N = 1e4 + 10;
int n;
int out[N], par[N], son[N];
int main() {ios::sync_with_stdio(false);cin.tie(), cout.tie();cin >> n;for (int i = 2, root; i <= n; ++i) {cin >> root;par[i] = root;++out[root];}for (int i = 2; i <= n; ++i) {if (out[i] == 0)++son[par[i]];}bool flag = true;for (int i = 1; i <= n; ++i) {if (out[i] != 0 && son[i] < 3){flag = false;break;}}if (flag)cout << "Yes" << endl;elsecout << "No" << endl;return 0;
}