1 //Accepted    1240 KB    250 ms 2 //水题 欧拉回路 3 //连通+节点度均为偶数 4 #include <cstdio> 5 #include <cstring> 6 #include <queue> 7 #include <iostream> 8 using namespace std; 9 const int imax_n = 1005;10 bool a[imax_n][imax_n];11 bool vis[imax_n];12 int cnt[imax_n];13 int n,m;14 queue<int >q;15 16 void bfs(int s)17 {18     while (!q.empty()) q.pop();19     q.push(s);20     vis[s]=true;21     while (!q.empty())22     {23         int x=q.front();24         q.pop();25         for (int i=1;i<=n;i++)26         {27             if (!vis[i] && a[x][i]==true)28             {29                 vis[i]=true;30                 q.push(i);31             }32         }33     }34 }35 int judge()36 {37     memset(vis,0,sizeof(vis));38     int ans=0;39     for (int i=1;i<=n;i++)40     {41         if (!vis[i]) ans++;42         if (ans>=2) return 0;43         bfs(i);44     }45     return 1;46 }47 int slove()48 {49     //printf("judge=%d\n",judge());50     if (judge()==0) return 0;51     for (int i=1;i<=n;i++)52     {53         if (cnt[i]%2!=0) return 0;54     }55     return 1;56 }57 int main()58 {59     while (scanf("%d",&n),n)60     {61         scanf("%d",&m);62         memset(cnt,0,sizeof(cnt));63         memset(a,false,sizeof(a));64         int x,y;65         for (int i=1;i<=m;i++)66         {67             scanf("%d%d",&x,&y);68             a[x][y]=a[y][x]=true;69             cnt[x]++;70             cnt[y]++;71         }72         printf("%d\n",slove());73     }74     return 0;75 }