More is better HDU

More is better

HDU - 1856

题意：给出n个关系，问最多有多少个人直接或者间接有关系．

并查集．

#include <bits/stdc++.h>
using namespace std;

const int maxn=10000010;
int f[maxn],rk[maxn];

int gf(int x){
    return x==f[x]?f[x]:f[x]=gf(f[x]);
}
int n;
int main(){
   // freopen("in.txt","r",stdin);
    while(scanf("%d",&n)!=EOF){
        int ans=0;
        for(int i=0;i<maxn;i++) f[i]=i,rk[i]=1;
        for(int i=0;i<n;i++){
            int a,b;
            scanf("%d %d",&a,&b);
            int pa=gf(a),pb=gf(b);
            if(pa!=pb){
                f[pa]=pb;
                rk[pb]+=rk[pa];
              //  ans=max(ans,rk[pb]);
            }
        }
        for(int i=1;i<maxn;i++) ans=max(ans,rk[i]);
        printf("%d
",ans);
    }
    return 0;
}