HDU-1213 How Many Tables

#include <bits/stdc++.h>
#define pb push_back
#define _for(i,a,b) for(int i = (a);i < (b);i ++)
#define INF 0x3f3f3f3f
#define sz size()

using namespace std;
typedef long long ll;
#define _for(i,a,b) for(int i = (a);i < (b);i ++)
const int maxn = 50003;
int par[maxn]; //父亲 
int high[maxn]; //树的高度
int n;
void init(int n)
{
    _for(i,0,n)
    {
        par[i] = i;
        high[i] = 0;
    }
} 

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

void unite(int x,int y)
{
    x = find(x);y = find(y);
    if(x==y) return ;
    n --;
    if(high[x]<high[y])
        par[x] = y;
    else
    {
        par[y] = x;
        if(high[x]==high[y])
            high[x] ++;
    }
}

bool same(int x,int y)
{
    return find(x) == find(y); 
}


int main()
{
    int T; 
    scanf("%d",&T);
    while(T--)
    {
        int N,M;
        scanf("%d %d",&N,&M);
        n = N;
        init(N+1);
        while(M--)
        {
            int a,b;
            scanf("%d %d",&a,&b);
            unite(a,b);
        }
        cout << n <<endl;
    }
    return 0;
}