uva10608-Friends

#include<stdio.h>
#include<string.h>
#include<algorithm>
#define N 30010
#define M 50010
using namespace std;

int cit[N], gro[N];

void make_set(int n)
{
    for (int i = 1; i <= n; i++)
        cit[i] = i;
}

int get_fa(int x)
{
    return (cit[x] == x) ? x : cit[x] = get_fa(cit[x]);
}

int main()
{
    int t;
    int n, m;
    scanf("%d", &t);
    while (t--) {
        scanf("%d%d", &n, &m);
        make_set(n);
        memset(gro, 0, sizeof(gro));
        for (int i = 0; i < m; i++) {
            int a, b;
            scanf("%d%d", &a, &b);
            int fa = get_fa(a);
            int fb = get_fa(b);
            cit[fa] = fb;
        }
        //需要整理各个并查集
        for (int i = 1; i <= n; i++) get_fa(i);
        for (int i = 1; i <= n; i++) gro[cit[i]]++;
        int maxn = 0;
        for (int i = 1; i <= n; i++) maxn = max(maxn, gro[i]);
        printf("%d\n", maxn);
    }
    return 0;
}