【杭电2120】有几个环

Ice_cream's world I

Time Limit:1000MS     Memory Limit:32768KB     64bit IO Format:%I64d & %I64u

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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

1
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#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
int n,m;
int f[1100];
int find(int x)
{
    if(x==f[x])
	return x;
	else
	{
		f[x]=find(f[x]);  
    return f[x];
	}     
}
int main()
{
    while(~scanf("%d%d",&n,&m))
	{
	for(int i=0;i<n;i++)	
        f[i]=i;    
        int ans=0;
        int a,b;
        while(m--){
            scanf("%d%d",&a,&b);
            int x=find(a);
            int y=find(b);
            if(x==y)//节点值相同，围成了一个环
                ans++;
            else
                f[x]=y;
        }
        printf("%d\n",ans);
    }
    return 0;
}