uva 10608(并查集)

题意就不描述了，最简单的并查集。秒掉就OK

代码如下：

#include <iostream>
#include <cstdio>
#include <string>
#include <cstdlib>
#include <algorithm>
#include <queue>
#include <stack>
#include <utility>
#define ll long long
#define LEN 1000100
#define INF 0x7fffffff

using namespace std;

int n, m;
int parent[LEN];

void init()
{
    for(int i=0; i<LEN; i++){
        parent[i] = -1;
    }
}

int Find(int x){
    return parent[x]<0?x:Find(parent[x]);
}

void Union(int a, int b){
    int pa = Find(a), pb = Find(b);
    if(pa!=pb){
        parent[pb] += parent[pa];
        parent[pa] = pb;
    }
}

int main()
{
//    freopen("in.txt", "r", stdin);

    int T, a, b;
    scanf("%d", &T);
    while(T--){
        init();
        scanf("%d%d", &n, &m);
        for(int i=0; i<m ;i++){
            scanf("%d%d", &a, &b);
            Union(a, b);
        }
        int ans = 0;
        for(int i=1; i<=n; i++){
            ans = min(ans, parent[i]);
        }
        cout << -ans << endl;
    }
    return 0;
}