HDU 2120 Ice_cream's world I

 

 

　　　　　　　　　　　　　　Ice_cream's world I

 

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

 

#include<cstdio>
using namespace std;

int bin[1005];
int count;

int find(int x)
{
    int r=x;
    while(bin[r]!=r)
    r=bin[r];
    int temp=x;
    while(temp!=r)
    {
        int j=bin[temp];
        bin[temp]=r;
        temp=j;
    }
    return r;
}

void merge(int x,int y)
{
    int fx=find(x);
    int fy=find(y);
    if(fx!=fy)
    bin[fy]=fx;
    else
    count++;
}

int main()
{
    //freopen("in.txt","r",stdin);
    int m,n,a,b;
    while(scanf("%d%d",&m,&n)!=EOF)
    {
        count=0;
        for(int i=0;i<m;i++)
        bin[i]=i;
        for(int i=0;i<n;i++)
        {
            scanf("%d%d",&a,&b);
            merge(a,b);
        }
        printf("%d\n",count);
    }
    return 0;
}