hdu1856 查并集

来源：互联网发布：韦德09年数据编辑：程序博客网时间：2024/05/21 14:44

对特殊情况总是考虑不周~~~当n=0应输出1;

http://acm.hdu.edu.cn/showproblem.php?pid=1856

#include <iostream>#include <cstring>#include <cstdio>using namespace std;int p[10000005];int vis[10000005];int maxx;inline void make_set(int n){    p[n]=n;}int find_set(int i){    int j=i;    while(j!=p[j])    {        j=p[j];    }    return p[i]=j;}int Union(int a,int b){    a=find_set(a);    b=find_set(b);    if(a==b)    {        //vis[a]++;        //if(vis[a]>maxx)           // maxx=vis[a];        return 0;    }    else    {        p[a]=b;        vis[b]+=vis[a];        if(vis[b]>maxx)            maxx=vis[b];        return 1;    }}int main(){    int n;    while(scanf("%d",&n)!=EOF)    {        int i;        maxx=0;        if(n==0)        {            printf("1\n");            continue;        }        memset(vis,0,sizeof(vis));        memset(p,0,sizeof(p));        for(i=0;i<n;i++)        {            int a,b;            scanf("%d%d",&a,&b);            if(!vis[a])            {                vis[a]=1;                make_set(a);            }            if(!vis[b])            {                vis[b]=1;                make_set(b);            }            Union(a,b);        }        printf("%d\n",maxx);    }    return 0;}