Ice_cream's world I

Time Limit: 3000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 872 Accepted Submission(s): 509


Problem Description ice_cream's world is a rich country, it has many fertile lands. Today, the queen of ice_cream wants award land to diligent ACMers. So there are some watchtowers are set up, and wall between watchtowers be build, in order to partition the ice_cream’s world. But how many ACMers at most can be awarded by the queen is a big problem. One wall-surrounded land must be given to only one ACMer and no walls are crossed, if you can help the queen solve this problem, you will be get a land.
Input In the case, first two integers N, M (N<=1000, M<=10000) is represent the number of watchtower and the number of wall. The watchtower numbered from 0 to N-1. Next following M lines, every line contain two integers A, B mean between A and B has a wall(A and B are distinct). Terminate by end of file.
Output Output the maximum number of ACMers who will be awarded.
One answer one line.
Sample Input

8 10
0 1
1 2
1 3
2 4
3 4
0 5
5 6
6 7
3 6
4 7

Sample Output

3

源代碼（並查集，判斷成環個數）

#include
#include
#include
using namespace std; 
int m,n;
int per[2000];

int find(int x)
{
   if(x==per[x])
   return x;
   return per[x]=find(per[x]);

}

int main()
{
   int i;
   while(scanf(%d%d,&n,&m)!=EOF)
   {
         for(i=0;i