[HDU 1213]How Many Tables

题目链接:

注意:从1开始循环,一定要循环到n啊(<=n)

#include<iostream>
#include<cstdio>
using namespace std;

const int maxn = 1010;
int ufs[maxn];

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

int FindRoot(int x) {
    return ufs[x] == x ? x : ufs[x] = FindRoot(ufs[x]);
}

bool Merge(int x,int y) {
    int a = FindRoot(x);
    int b = FindRoot(y);
    if(a == b)
        return false;
    else
    {
        ufs[b] = a;
        return true;
    }
}

int main() {
    int n,m;
    int t;
    scanf("%d",&t);
    while(t--) {
        scanf("%d%d",&n,&m);
        Init(n);
        int x,y;
        while(m--) {
            scanf("%d%d",&x,&y);
            if(Merge(x,y))
                n--;
        }
        printf("%d
",n);
    }
    return 0;
}