> 可否麻烦各位大牛看一下究竟这组代码到底是在哪里RE的? 是因为递回过深吗!? 难道记忆化搜索也无法吗...
> 
> #include<ctime>
> #include<cstdio>
> #include<cstdlib>
> #include<vector>
> #include<utility>
> #include<functional>
> #include<algorithm>
> #define PB push_back
> #define MP make_pair
> #define _F first
> #define _S second
> 
> using namespace std;
> 
> typedef long long int ll;
> typedef pair<int, ll> pii;
> const long long int INF = 2000000000;
> vector<pii> Edge[200200];
> long long int DP1[200200], DP2[200200];
> int root, par[200200], parS[200200];
> long long int con[200200];
> 
> void init(void){
>     for(int i = 0; i < 200100; i++){
>         if(Edge[i].size()) Edge[i].clear();
>         DP1[i] = 0;
>         DP2[i] = -1;
>         con[i] = 0;
>         parS[i] = 0;
>         par[i] = 0;
>         root = 0;
>         }
>     return;
>     }
> 
> ll __MN(ll A, ll B){
>     if(A > B) return B;
>     return A;
>     }
> ll __MX(ll A, ll B){
>     if(A > B) return A;
>     return B;
>     }
> 
> void DFS1(int now, int pre){
>     par[now] = pre;
>     if(now!=root && Edge[now].size()==1){
>         DP1[now] = INF;
>         return;
>         }
>     for(int i = 0; i < Edge[now].size(); i++){
>         pii nxt = Edge[now][i];
>         
>         if(nxt._F == pre) continue;
>         parS[nxt._F] = nxt._S;
>         DFS1(nxt._F, now);
>         con[nxt._F] = __MN(DP1[nxt._F], nxt._S);
>         DP1[now] += con[nxt._F];
>         if(DP1[nxt._F] == INF) DP1[nxt._F] = 0;
>         }
>     return;
>     }
> 
> void DFS2(int now){
>     
>     if(now == root) return;//if(now < 0) while(1);
>     if(now < 0) return;
>     if(par[now] < 0) return;
>     
>     if(DP2[now] != -1) return;
>     if(DP2[par[now]] == -1) DFS2(par[now]);
>     if(Edge[now].size() == 1){
>         DP2[now] = __MN(Edge[now][0]._S, DP2[par[now]]);
>         return;
>         }
>     if(par[now]==root && Edge[par[now]].size()==1){
>         DP2[now] = Edge[par[now]][0]._S+DP1[now];
>         return;
>         }
>     DP2[now] = __MN(DP2[par[now]]-con[now], parS[now])+DP1[now];
> 
>     return;
>     }
> 
> int main(void){
>     int T;
>     srand(time(NULL));
>     scanf("%d", &T);
> 
>     while(T--){
>         int N, x, y;
>         long long int z;
>         scanf("%d", &N);
>         init();
>         for(int i = 0; i < N-1; i++){
>             scanf("%d%d%lld", &x, &y, &z);
>             Edge[x].PB(MP(y, z));
>             Edge[y].PB(MP(x, z));
>             }
>         root = rand()%N;
>         root++;
>         
>         par[root] = -1;
>         DFS1(root, -1);
>         
>         
>         DP2[root] = DP1[root];
>         
>         for(int i = 1; i <= N; i++) DFS2(i);
>         
>         long long int ans = 0;
>         for(int i = 1; i <= N; i++)
>             ans = __MX(ans, DP2[i]);
>         printf("%lld\n", ans);
>         }
> 
>     return 0;
>     }

你的Edge没有清空