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.
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 the maximum number of ACMers who will be awarded.
One answer one line.
8 10
0 1
1 2
1 3
2 4
3 4
0 5
5 6
6 7
3 6
4 7
#include<stdio.h>
int father[10010];
int find(int r)
{
if(r!=father[r])
return find(father[r]);
else
return father[r];
}
int main()
{
int n,m;
while(~scanf("%d%d",&n,&m))
{
int a,b,count=0;
while(m--)
{
scanf("%d%d",&a,&b);
int fa=find(a);
int fb=find(b);
if(fa==fb)
count++;//判断是否有环,有的话,两者的父节点应该相等
else
father[fa]=fb;
}
printf("%d\n",count);
}
return 0;
}