C :

#include <stdio.h>
int i,j,n,m,a[1001],b[1001],c[1001];
void make_set()
{
	scanf("%d%d",&n,&m);
        for(i=1;i<=m;i++)
                scanf("%d%d",&a[i],&b[i]);
        for(i=1;i<=n;i++)
                c[i]=i;
}
void count()
{
	j=1;
    while(j==1)
    {
		j=0;
        for(i=1;i<=m;i++)
        {
			if(c[a[i]]<c[b[i]])
            {
				j=1;
				c[b[i]]=c[a[i]];
            }
            if(c[a[i]]>c[b[i]])
            {
				j=1;
				c[a[i]]=c[b[i]];
            }
		}
	}
}
void print()
{
	j=0;
    for(i=1;i<=n;i++)
	{
		if(c[i]==i)
			j++;
	}
    printf("%d\n",j);
}
int main()
{
        int t;
        scanf("%d",&t);
        while(t--)
        {
			make_set();
			count();
			print();
        }
        return 0;
}

C++ :

#include <stdio.h>
int run()
{
	int n,m,a[1111],b[1111],c[1111],i,j,k;
	scanf("%d%d",&n,&m);
	for(i=1;i<=m;i++)
		scanf("%d%d",&a[i],&b[i]);
	for(i=1;i<=n;i++)
		c[i]=i;
	k=1;
	while(k==1)
	{
		k=0;
		for(i=1;i<=m;i++)
		{
			if(c[a[i]]<c[b[i]])
			{
				k=1;
				c[b[i]]=c[a[i]];
			}
			if(c[a[i]]>c[b[i]])
			{
				k=1;
				c[a[i]]=c[b[i]];
			}
		}
	}
	j=0;
	for(i=1;i<=n;i++)
		if(c[i]==i)
			j++;
	printf("%d\n",j);
}
int main()
{
	int t;
	scanf("%d",&t);
	while(t!=0)
	{
		t--;
		run();
	}
	return 0;
}

Java :

import java.io.*;
import java.util.*;

public class Main{
 static boolean b[]=new boolean[1005];
  static int f[]=new int[1005],r[]=new int[1005];
  static int getfather(int n){
   return f[n]=f[n]==n?n:getfather(f[n]); 
  }
  static void Union(int fa,int fb){
    if(r[fa]>=r[fb]){
     f[fb]=f[fa];r[fa]+=r[fb];
    }else{
     f[fa]=f[fb];r[fb]+=r[fa];
    }return;
  }
  public static void main(String args[]){
   Scanner jin=new Scanner(System.in);
    while(true){
     int T=jin.nextInt();
      while(T-->0){
       int N=jin.nextInt(),M=jin.nextInt();
        for(int i=1;i<=N;i++){
         r[i]=1;f[i]=i;b[i]=false; 
        }
        for(int i=0;i<M;i++){
         int A=jin.nextInt(),B=jin.nextInt();
          int fa=getfather(A),fb=getfather(B);
          if(fa!=fb)Union(fa,fb);
        }
        int cnt=0;
        for(int i=1;i<=N;i++)
          if(!b[getfather(i)]){
         b[getfather(i)]=true;
          cnt++;
        }
        System.out.println(cnt);
      }
    }
  }
}

Python :

def space_input():
    s=raw_input().split()
    for i in range(len(s)):
        s[i]=eval(s[i])
    return tuple(s)
def main():
    try:
        n,p=space_input()
    except:
        n,p=space_input()
    friends=[{i} for i in range(1,n+1)]
    for i in range(p):
        a,b=space_input()
        contact={}
        for number in (a,b):
            for j in range(n):
                if number in friends[j]:
                    contact[number]=j
        if contact[a]<contact[b]:
            friends[contact[a]]=friends[contact[a]]|friends.pop(contact[b])
            n-=1
        elif contact[b]<contact[a]:
            friends[contact[b]]=friends[contact[b]]|friends.pop(contact[a])
            n-=1
    print len(friends)
t=input()
for i in range(t):
    main()