图论基础UVA10054

#include<stdio.h>#include<string.h>#include<stdlib.h>const int maxn=55,maxm=1010;int a[maxn][maxn],num[maxn],ans[maxm];int n,m;void dfs(int x){for(int i=1;i<=50;i++){if(a[x][i]){a[x][i]--;a[i][x]--;dfs(i);}}ans[++m]=x;}int main(){#ifndef ONLINE_JUDGEfreopen("uva10054.in","r",stdin);//freopen("uva10054.out","w",stdout);#endifint i,j,k,T;int x,y,u,flag;scanf("%d",&T);for(u=1;u<=T;u++){if(u>1)printf("\n");printf("Case #%d\n",u);memset(a,0,sizeof(a));memset(num,0,sizeof(num));flag=1;m=0;scanf("%d",&n);for(i=1;i<=n;i++){scanf("%d%d",&x,&y);a[x][y]++;a[y][x]++;num[x]++;num[y]++;}int p;for(i=1;i<=50;i++){if(num[i]%2!=0){flag=0;break;}if(num[i])p=i;}if(flag)dfs(p);if(!flag || m!=n+1)printf("some beads may be lost\n");elsefor(i=1;i<m;i++)printf("%d %d\n",ans[i],ans[i+1]);}return 0;}