zoj 3261 Connections in Galaxy War

http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemCode=3261

先把不需要destroy的边连上 然后逆序寻找答案 遇到destroy 的边就连上

过程中用并查集维护答案

代码：

#include<iostream>
#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>
#include<vector>
#include<set>
#include<map>
#include<string>
#include<queue>
#include<stack>
#include <iomanip>
using namespace std;
#define LL long long
const double eps=1e-6;
const int INF=0x3f3f3f3f;
const int N=10005;
const int M=50005;
int a[N],f[N];
struct node
{
    int l,r;
}edge[M],Q[M];
int had[M];
typedef pair<int,int>pairedge;
set<pairedge>st;
int fx(int x)
{
    if(f[x]!=x)
    f[x]=fx(f[x]);
    return f[x];
}
void toge(int l,int r)
{
    int L=fx(l);
    int R=fx(r);
    if(L!=R)
    {
        if(a[L]>a[R]||(a[L]==a[R]&&L<R))
        f[R]=L;
        else
        f[L]=R;
    }
}
int main()
{
    //freopen("data.in","r",stdin);
    int n;
    int I=0;
    while(scanf("%d",&n)!=EOF)
    {
        if(I++>0)
        printf("\n");
        for(int i=0;i<n;++i)
        scanf("%d",&a[i]);
        int m;
        scanf("%d",&m);
        for(int i=0;i<m;++i)
        {
            scanf("%d %d",&edge[i].l,&edge[i].r);
            if(edge[i].l>edge[i].r)
            swap(edge[i].l,edge[i].r);
        }
        int q;
        scanf("%d",&q);
        st.clear();
        for(int i=0;i<q;++i)
        {
            getchar();
            char s[10];
            scanf("%s",s);
            if(s[0]=='q')
            Q[i].l=-1;
            else
            scanf("%d",&Q[i].l);
            scanf("%d",&Q[i].r);
            if(Q[i].l!=-1)
            {
                if(Q[i].l>Q[i].r)
                swap(Q[i].l,Q[i].r);
                st.insert(pairedge(Q[i].l,Q[i].r));
            }
        }
        for(int i=0;i<n;++i)
        f[i]=i;
        for(int i=0;i<m;++i)
        {
            if(st.find(pairedge(edge[i].l,edge[i].r))==st.end())
            {
                toge(edge[i].l,edge[i].r);
            }
        }
        memset(had,0,sizeof(had));
        for(int i=q-1;i>=0;--i)
        {
            if(Q[i].l!=-1)
            toge(Q[i].l,Q[i].r);
            else
            {
                Q[i].l=fx(Q[i].r);
                if(a[Q[i].l]>a[Q[i].r])
                had[i]=1;
                else
                had[i]=-1;
            }
        }
        for(int i=0;i<q;++i)
        {
            if(had[i]==0) continue;
            if(had[i]==1) printf("%d\n",Q[i].l);
            else printf("-1\n");
        }

    }
    return 0;
}