UVa 10054 (打印欧拉回路) The Necklace

#include <cstdio>
#include <cstring>

const int maxn = 50 + 5;
int G[maxn][maxn], deg[maxn];

void Euler(int u)
{
for(int v = 1; v <= 50; v++) if(G[u][v])
{
G[u][v]--; G[v][u]--;
Euler(v);
printf("%d %d\n", v, u);
}
}

int main()
{
//freopen("in.txt", "r", stdin);

int T; scanf("%d", &T);
for(int kase = 1; kase <= T; kase++)
{
memset(G, 0, sizeof(G));
memset(deg, 0, sizeof(deg));

if(kase > 1) puts("");
printf("Case #%d\n", kase);

int n, a, b, st;
scanf("%d", &n);
for(int i = 0; i < n; i++)
{
scanf("%d%d", &a, &b);
st = a;
deg[a]++; deg[b]++;
G[a][b]++; G[b][a]++;
}

bool ok = true;
for(int i = 1; i <= 50; i++) if(deg[i] % 2) { ok = false; break; }
if(!ok) { puts("some beads may be lost"); continue; }

Euler(st);

}

return 0;
}