zoj 3195

Posted 2020-07-03 AC菜鸟机

http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemId=3320

离线算法RE了..

#include<stdio.h>
#include<iostream>
#include<string.h>
#include<math.h>
#include<algorithm>
using namespace std;
const int N = 50005;
const int M =100005;
struct Edge{
    int u,v,w,next;
}e[2*N];
struct Q_Edge{
    int u,v,next,lca;
}eq[2*M];
int head[N];
int _head[N];
int dis[N];
int vis[N];
int ances[N];
int father[N];
void addedge(int u,int v,int w,int &k){
    e[k].u = u;e[k].v = v;e[k].w= w;
    e[k].next = head[u];head[u]=k++;
}
void add_qedge(int u,int v,int &k){
    eq[k].u = u;eq[k].v = v;eq[k].lca = -1;
    eq[k].next = _head[u];_head[u]=k++;
}
int _find(int u){
    if(u==father[u]) return father[u];
    return father[u] = _find(father[u]);
}
void unions(int u,int v){
    int x = _find(u),y = _find(v);
    father[x]=y;
}
void Targin(int u){
    vis[u] = true;
    ances[u]=father[u] = u;
    for(int k = head[u];k!=-1;k=e[k].next){
        if(!vis[e[k].v]){
            int v = e[k].v,w = e[k].w;
            dis[v] = dis[u]+w;
            Targin(v);
            unions(v,u);
            ances[_find(u)] = u;
        }
    }
    for(int k = _head[u];k!=-1;k=eq[k].next){
        if(vis[eq[k].v]){
            int v = eq[k].v;
            eq[k].lca = eq[k^1].lca = ances[_find(v)];
        }
    }
}
int main()
{
    int n;
    while(scanf("%d",&n)!=EOF){

        memset(head,-1,sizeof(head));
        memset(_head,-1,sizeof(_head));

        int tot=0;
        for(int i=1;i<n;i++){
            int u,v,w;
            scanf("%d%d%d",&u,&v,&w);
            addedge(u,v,w,tot);
            addedge(v,u,w,tot);
        }
        tot = 0;
        int m;
        scanf("%d",&m);
        for(int i=0;i<m;i++){
            int a,b,c;
            scanf("%d%d%d",&a,&b,&c);
            add_qedge(a,b,tot);
            add_qedge(b,a,tot);
            add_qedge(a,c,tot);
            add_qedge(c,a,tot);
            add_qedge(b,c,tot);
            add_qedge(c,b,tot);

        }
        memset(vis,0,sizeof(vis));
        dis[0]=0;
        Targin(0);
        int a[3];
        for(int i=0;i<m;i++){
            int s = i*6;
            a[0] = dis[eq[s].u]+dis[eq[s].v]-2*dis[eq[s].lca];  ///a->b
            a[1] = dis[eq[s+2].u]+dis[eq[s+2].v]-2*dis[eq[s+2].lca]; ///a->c
            a[2] = dis[eq[s+4].u]+dis[eq[s+4].v]-2*dis[eq[s+4].lca]; ///b->c
            //sort(a,a+3);
            printf("%d\n",(a[2]+a[1]+a[0])/2);

        }
        printf("\n");
    }

}