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

Sample Output

源代码（并查集，判断成环个数）

#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
     
      ?

hdu 2120 Ice_cream's world I

Ice_cream's world I