UVA 10608 Friends

#include <map>
#include <set>
#include <list>
#include <cmath>
#include <ctime>
#include <deque>
#include <stack>
#include <queue>
#include <cctype>
#include <cstdio>
#include <string>
#include <vector>
#include <climits>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <algorithm>
#define LL long long
#define PI 3.1415926535897932626
using namespace std;
int gcd(int a, int b) {return a % b == 0 ? b : gcd(b, a % b);}
#define MAXN 30010
int N,M;
int p[MAXN],num[MAXN];
int Find(int x) {return x == p[x] ? x : p[x] = Find(p[x]);}
int main()
{
    //freopen("sample.txt","r",stdin);
    int T;
    scanf("%d",&T);
    while (T--)
    {
        scanf("%d%d",&N,&M);
        int ans = 0;
        for (int i = 0; i <= N; i++) {p[i] = i; num[i] = 1;}
        while (M--)
        {
            int u,v;
            scanf("%d%d",&u,&v);
            int x = Find(u);
            int y = Find(v);
            if (x != y)
            {
                if (num[x] > num[y])
                {
                    p[y] = x;
                    num[x] += num[y];
                }
                else
                {
                    p[x] = y;
                    num[y] += num[x];
                }
                ans = max(ans,max(num[x],num[y]));
            }
        }
        printf("%d\n",ans);
    }
    return 0;
}