ZOJ3261 Connections in Galaxy War 并查集

分析：对于这种删边操作，我们通常可以先读进来，然后转化离线进行倒着加边

#include <stdio.h>
#include <string.h>
#include <algorithm>
#include <iostream>
using namespace std;
typedef pair<int,int>pii;
const int N=1e4+5;
pii p[N<<1];
int v[N],fa[N],n,m,q;
bool vis[N<<1];
struct Ask{
  int op,id,ans;
}ask[N*5];
int find(int x){
  return x==fa[x]?x:fa[x]=find(fa[x]);
}
void Union(int x,int y){
  x=find(x),y=find(y);
  if(x==y)return;
  if(v[x]>v[y]||(v[x]==v[y]&&x<y))fa[y]=x;
  else fa[x]=y;
}
int main()
{
    bool flag=1;
    while(~scanf("%d",&n)){
       if(flag)flag=0;
       else printf("
");
       for(int i=0;i<n;++i){
        scanf("%d",&v[i]),fa[i]=i;
       }
       memset(vis,0,sizeof(vis));
       scanf("%d",&m);
       for(int i=1;i<=m;++i){
          scanf("%d%d",&p[i].first,&p[i].second);
          if(p[i].first>p[i].second)swap(p[i].first,p[i].second);
       }
       sort(p+1,p+1+m);
       scanf("%d",&q);
       for(int i=1;i<=q;++i){
          char s[10];
          int u,v;
          scanf("%s%d",s,&u);
          if(s[0]=='q'){
            ask[i].op=1;
            ask[i].id=u;
          }
          else{
            ask[i].op=2;
            scanf("%d",&v);
            if(u>v)swap(u,v);
            ask[i].id=lower_bound(p+1,p+1+m,make_pair(u,v))-p;
            vis[ask[i].id]=1;
          }
       }
       for(int i=1;i<=m;++i){
        if(vis[i])continue;
         Union(p[i].first,p[i].second);
       }
       for(int i=q;i>0;--i){
         if(ask[i].op==1){
            ask[i].ans=find(ask[i].id);
            if(v[ask[i].ans]==v[ask[i].id])ask[i].ans=-1;
         }
         else Union(p[ask[i].id].first,p[ask[i].id].second);
       }
       for(int i=1;i<=q;++i)if(ask[i].op==1)printf("%d
",ask[i].ans);
    }
    return 0;
}