UVA 10608 Friends

并查集

 

CODE：

 

#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;
const int maxn=30010;
int p[maxn];
int rank[maxn];
int n, m;

int find(int x)
{
    return p[x] == x? x: p[x] = find(p[x]);
}

void Union(int x, int y)
{
       int i = find(x), j = find(y);
    if(i == j) return ;
    if(rank[i] > rank[j])
    {
        p[j] = i;
        rank[i] += rank[j]; 
    }
    else
    {
        p[i] = j;
        rank[j] += rank[i];
    }
}

void init()
{
    for(int i = 1; i <= n; i++) rank[i] = 1;
    for(int i = 1; i <= n; i++) p[i] = i;
}

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