Friends--并查集

#include <map>#include <queue>#include <cmath>#include <cstdio>#include <cstring>#include <stdlib.h>#include <iostream>#include <algorithm>#define maxn 30100using namespace std;int set[maxn],sum[maxn],imax;int set_find(int d){    if(set[d]<0)        return d;    else return set_find(set[d]);}void join(int a,int b){    int x=set_find(a);    int y=set_find(b);    if(x!=y){        set[x]=y;        sum[y]+=sum[x];        imax=sum[y]>imax?sum[y]:imax;    }}int main(){    int loop;    scanf("%d",&loop);    while(loop--){        int x,y,n,m;        scanf("%d%d",&n,&m);         for(int i=0;i<n;++i){                sum[i]=1;                set[i]=-1;        }        imax=0;        while(m--){            scanf("%d%d",&x,&y);            join(x,y);        }        printf("%d\n",imax);    }    return 0;}