题解：

 

（并查集处理往上跳的时候，一定要先让u,v往上跳到并查集的祖先，不然会wa掉）

代码如下：

#include 
     
      #include 
      
       #include 
       
        #include 
        
         #include 
         
          using namespace std;const int maxn = 1e5 + 100;typedef long long LL;int f[maxn], g[maxn], p[maxn], deep[maxn];LL W[maxn];int ffind(int x) { return f[x] == x ? f[x] : f[x] = ffind(f[x]); }int gfind(int x) { return g[x] == x ? g[x] : g[x] = gfind(g[x]); }struct Line{    int u1, v1, u2, v2;    int cost;    bool operator <(const Line& B) const{        return cost < B.cost;    }};vector
          
            G[maxn];vector
           
             V;void dfs(int x, int fa, int d){ deep[x] = d; p[x] = fa; for(int i = 0; i < G[x].size(); i++){ int to = G[x][i]; if(to == fa) continue; dfs(to, x, d+1); }}void Merge(int u, int v, LL w){ u = ffind(u); v = ffind(v); while(ffind(u) != ffind(v)){ if(deep[u] < deep[v]) swap(u, v); int fa = ffind(u); u = p[fa]; f[fa] = ffind(u); u = ffind(u); if(gfind(fa) != gfind(u)){ W[gfind(u)] += (W[gfind(fa)] + w); g[gfind(fa)] = gfind(u); } }}int main(){ int T, n, m, x, y; cin>>T; while(T--){ cin>>n>>m; memset(W, 0, sizeof(W)); for(int i = 1; i <= n; i++) g[i] = f[i] = i; for(int i = 1; i <= n; i++) G[i].clear(); V.clear(); V.resize(m); for(int i = 1; i < n; i++){ scanf("%d %d", &x, &y); G[x].push_back(y); G[y].push_back(x); } dfs(1, 1, 1); for(int i = 0; i < m; i++){ scanf("%d %d %d %d %d", &V[i].u1, &V[i].v1, &V[i].u2, &V[i].v2, &V[i].cost); } sort(V.begin(), V.end()); for(int i = 0; i < V.size(); i++){ Line line = V[i]; int u = line.u1, v = line.v1, lca1, lca2; Merge(u, v, line.cost); lca1 = ffind(u); u = line.u2, v = line.v2; Merge(u, v, line.cost); lca2 = ffind(u); if(gfind(lca1) != gfind(lca2)) { W[gfind(lca2)] += (W[gfind(lca1)] + line.cost); g[gfind(lca1)] = gfind(lca2); } } int num = 0; for(int i = 1; i <= n; i++) if(gfind(i) == gfind(1)) num++; cout<
            
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