3 3
1 2
1 3
2 3
3 2
1 2
2 3
0

样例输出：

1

0

#include 
           
            
using namespace std;
const int max = 1001;
int G[max][max];
int du[max];
bool visite[max];
int n, m;
bool judge()
{
	for (int i = 1; i <= n; i++)
	{
		if (du[i] % 2 != 0 || du[i] == 0)
			return false;
	}
	return true;
}

void DFS(int start, int &counts)
{
	for (int i = 1; i <= n; i++)
	{
		if (G[start][i] && !visite[i])
		{
			counts++;
			visite[i] = true;
			DFS(i, counts);
		}
	}
}

int main()
{
	int s, e, counts;
	cin >> n;
	while (n!=0)
	{
		counts = 1;
		for (int i = 0; i <= n;i++)
		for (int j = 0; j <= n; j++)
		{
			G[i][j] = 0;
		}
		for (int i=0;i<=n;i++)
		{
			du[i] = 0;
			visite[i] = false;
		}
		cin >> m;
		for (int i = 0; i 
            
             > s >> e; G[s][e] = 1; G[e][s] = 1; du[s]++; du[e]++; } visite[1] = true;; DFS(1, counts); if (counts == n&&judge()) cout << "1" << endl; else cout << "0" << endl; cin >> n; } return 0; }