学步园

题目地址：点击打开链接

#include <iostream>
using namespace std;
const int maxsize = 210;
int f[maxsize];
int degree[maxsize];
int find_father(int x)
{
	if(f[x]==-1||f[x]==-2)
	{
		f[x]=-1;
		return x;
	}
	else
		return find_father(f[x]);
}
void Union(int a,int b)
{
	int father_a=find_father(a);
	int father_b=find_father(b);
	if(father_a!=father_b)
		f[father_a]=father_b;
}
int main()
{
	int N,R;
	while(cin>>N>>R)
	{
		int i;
		for(i=0;i<maxsize;++i)
		{
			f[i]=-2;
			degree[i]=0;
		}
		while(R--)
		{
			int a,b;
			cin>>a>>b;
			++degree[a];
			++degree[b];
			Union(a,b);
		}
		int num=0;
		for(i=0;i<maxsize;++i)
		{
			if(f[i]==-1)
				++num;
			if(degree[i]%2!=0)
				break;
		}
		if(num==1&&i==maxsize)
			cout<<"Possible"<<endl;
		else
			cout<<"Not Possible"<<endl;
	}
	return 0;
}