hdu 1272

808075

asia2562219

B

Accepted

1172 KB

31 ms

C++

1299 B

2012-11-10 20:19:31

水爆了 Yes 一直写成 YES————！

并查集～

#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <algorithm>
#include <iostream>
using namespace std;
#define MAXN 111111
int deg[MAXN],tot,father[MAXN],totnum,tote;
bool flag=true;
int find(int x)
{
    int temp=x;
    while(temp!=father[temp])
    temp=father[temp];
    int i=x,j;
    while(i!=temp)
    {
        j=father[i];
        father[i]=temp;
        i=j;
    }
    return temp;
}
bool judge()
{
    if(!flag)return false;
    int odd=0,rot;
    if(tote==0&&totnum==0)return true;
    if(tote!=totnum-1)return false;
    rot=find(tot);
    for(int i=1;i<=tot;i++)
        if(deg[i]!=0&&rot!=find(i))return false;
    return true;
}
int main()
{
    int x,y,i;
    tot=0;memset(deg,0,sizeof(deg));
    for(i=0;i<=MAXN;i++)father[i]=i;
    totnum=tote=0;
    while(scanf("%d%d",&x,&y),x!=-1)
    {
        if(x==0&&y==0)
        {if(judge())cout<<"Yes"<<endl;
            else cout<<"No"<<endl;
        tot=0;memset(deg,0,sizeof(deg));
        flag=true;
        for(i=0;i<=MAXN;i++)father[i]=i;
        totnum=tote=0;continue;}
        tot=max(max(tot,x),y);
        if(deg[x]==0)totnum++;
        if(deg[y]==0)totnum++;
        tote++;
        deg[x]++;deg[y]++;
        if(find(x)!=find(y))
        father[find(x)]=find(y);
        else flag=false;
    }
    return 0;
}