UVA10054_The Necklace

#include <iostream>
#include <cstring>
#include <cstdio>
using namespace std;

int a[51][51],n=50,d[51],m,T;

void dfs(int x)
{
    for (int i=1; i<=n; i++)
        if (a[x][i])
        {
            a[x][i]--,a[i][x]--;
            dfs(i);
            printf("%d %d\n",i,x);
        }
}

int main()
{
    int cas=0,U,V;
    scanf("%d",&T);
    while (T--)
    {
        memset(d,0,sizeof d);
        memset(a,0,sizeof a);
        scanf("%d",&m);
        while (m--)
        {
            scanf("%d%d",&U,&V);
            a[U][V]++,a[V][U]++;
            d[U]++,d[V]++;
        }
        bool ans=true;
        for (int i=1; i<=n; i++)
            if (d[i]&1) ans=false;
        if (cas) printf("\n");
        printf("Case #%d\n",++cas);
        if (!ans) printf("some beads may be lost\n");
            else dfs(U);
    }
    return 0;
}