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;

}