hdu 2586 How far away ？ 离线LCA

#include <iostream>
#include <string.h>
#include <stdio.h>
using namespace std;
const int maxn=40005;
const int maxm=80005;
struct enode {
    int to,next,w;
} edges[maxm];
struct qnode {
    int to,next,id;
} query[405];
//dist[] 节点到根节点的距离
int head_e[maxn],head_q[maxn],f[maxn],vis[maxn],dist[maxn],res[405];
int n,m,u,v,w,cnte=0,cntq=0;//n个节点 m个询问
inline void addedge(int u, int v, int w) {
    edges[cnte].w=w;
    edges[cnte].to=v;
    edges[cnte].next=head_e[u];
    head_e[u]=cnte++;
}
inline void addque(int u, int v, int id) {
    query[cntq].id=id;
    query[cntq].to=v;
    query[cntq].next=head_q[u];
    head_q[u]=cntq++;
}
inline void init() {
    memset(head_e,-1,sizeof(head_e));
    memset(head_q,-1,sizeof(head_q));
    memset(vis,0,sizeof(vis));
    memset(dist,0,sizeof(dist));
    for(int i=1; i<=n; ++i) f[i]=i;
}
int Find(int x) {
    return x==f[x] ? x : f[x]=Find(f[x]);
}
void tarjan(int s) {
    vis[s]=1;
    for(int i=head_e[s]; i!=-1; i=edges[i].next) {
        if(!vis[edges[i].to]) {
            dist[edges[i].to]=dist[s]+edges[i].w;//跟新到根的距离
            tarjan(edges[i].to);
            f[edges[i].to]=s;
        }
    }
    for(int i=head_q[s]; i!=-1; i=query[i].next) {
        if(vis[query[i].to]==1) {
            int z=Find(query[i].to);
            //先减去再相加
            res[query[i].id]=dist[s]-dist[z]-dist[z]+dist[query[i].to];
        }
    }
}
int main() {
    ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
    int t; cin>>t;
    while(t--) {
        cin>>n>>m;
        init();
        for(int i=1; i<n; ++i) {
            cin>>u>>v>>w;
            addedge(u,v,w);
            addedge(v,u,w);
        }
        for(int i=1; i<=m; ++i) {
            cin>>u>>v;
            addque(u,v,i);
            addque(v,u,i);
        }
        dist[1]=0;
        tarjan(1);
        for(int i=1; i<=m; ++i) cout<<res[i]<<endl;
    }
    return 0;
}