loj 1357(树形dp)

题目链接：http://lightoj.com/volume_showproblem.php?problem=1357

 #define _CRT_SECURE_NO_WARNINGS
 #include <iostream>
 #include <cstdio>
 #include <cstring>
 #include <algorithm>
 #include <vector>
 using namespace std;

 const int MAXN = ( + );
 typedef long long ll;
 int n;
 ll child[MAXN];
 ll ans;
 vector<int >g[MAXN];

 ll dfs(int u)
 {
     ll ret = ;
     for (int i = ; i < (int)g[u].size(); i++) {
         int v = g[u][i];
         dfs(v);
         ans += ret * (child[v] + );
         ret += child[v] + ;
     }
     return child[u] = ret;
 }

 int main()
 {
     int _case, t = ;
     scanf("%d", &_case);
     while (_case--) {
         scanf("%d", &n);
         for (int i = ; i <= n; i++) g[i].clear();
         for (int i = ; i < n; i++) {
             int u, v;
             scanf("%d %d", &u, &v);
             g[u].push_back(v);
         }
         memset(child, , sizeof(child));
         ans = ;
         dfs();
         printf("Case %d: %d %lld\n", t++, n - , ans);

     }
     return ;
 }