J - A Bug's Life

Background
Professor Hopper is researching the sexual behavior of a rare species of bugs. He assumes that they feature two different genders and that they only interact with bugs of the opposite gender. In his experiment, individual bugs and their interactions were easy to identify, because numbers were printed on their backs.
Problem
Given a list of bug interactions, decide whether the experiment supports his assumption of two genders with no homosexual bugs or if it contains some bug interactions that falsify it.

Input
The first line of the input contains the number of scenarios. Each scenario starts with one line giving the number of bugs (at least one, and up to 2000) and the number of interactions (up to 1000000) separated by a single space. In the following lines, each interaction is given in the form of two distinct bug numbers separated by a single space. Bugs are numbered consecutively starting from one.

Output
The output for every scenario is a line containing "Scenario #i:", where i is the number of the scenario starting at 1, followed by one line saying either "No suspicious bugs found!" if the experiment is consistent with his assumption about the bugs' sexual behavior, or "Suspicious bugs found!" if Professor Hopper's assumption is definitely wrong.

Sample Input
2
3 3
1 2
2 3
1 3
4 2
1 2
3 4

Sample Output
Scenario #1:
Suspicious bugs found!

Scenario #2:
No suspicious bugs found!

Hint
Huge input,scanf is recommended.

题意：
给定n只虫子 不同性别的可以在一起 相同性别的不能在一起
给你m对虫子 判断中间有没有同性别在一起的；
我们把同性的放到一个集合里 如果一个集合里出现了异性 则说明存在同性恋在一起
假设 x 为一种性别 x + n 为与其相反的性别
若a,b为同性 的 我们则可以把判断 (a，b+n) (b,a+n)为异性反之亦然；

题解：
扩展域并查集

代码：

#include <iostream>
#include <cstdio>
#include <algorithm>
using namespace std;
const int maxn = 4010;
int p[maxn];
int t, n, m;

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

void Union(int a, int b){
  int x = find(a);
  int y = find(b);
  if(x != y)  p[x] = y;
}

bool judge(int x, int y){
  x = find(x);
  y = find(y);
  if(x != y)  return true;
  else return false;
}

int main()
{
  scanf("%d",&t);

  for(int i = 1; i <= t; i ++){
    scanf("%d%d",&n,&m);
    for(int i = 0; i <= 2 * n; i ++)
      p[i] = i;
    bool f = 1;
    int x, y;
    while(m --){
      scanf("%d%d",&x,&y);
      if(judge(x, y) || judge(x + n , y + n)){
        Union(x, y + n);
        Union(x + n, y);
      }
      else
        f = 0;
    }
    if(i != 1)  puts(" ");
    printf("Scenario #%d:\n", i);
    puts(f ? "No suspicious bugs found!" : "Suspicious bugs found!");
  }
  return 0;
}