UVa 10054 (打印欧拉回路) The Necklace

 1 #include <cstdio>
 2 #include <cstring>
 3 
 4 const int maxn = 50 + 5;
 5 int G[maxn][maxn], deg[maxn];
 6 
 7 void Euler(int u)
 8 {
 9     for(int v = 1; v <= 50; v++) if(G[u][v])
10     {
11         G[u][v]--; G[v][u]--;
12         Euler(v);
13         printf("%d %d\n", v, u);
14     }
15 }
16 
17 int main()
18 {
19     //freopen("in.txt", "r", stdin);
20 
21     int T; scanf("%d", &T);
22     for(int kase = 1; kase <= T; kase++)
23     {
24         memset(G, 0, sizeof(G));
25         memset(deg, 0, sizeof(deg));
26 
27         if(kase > 1) puts("");
28         printf("Case #%d\n", kase);
29 
30         int n, a, b, st;
31         scanf("%d", &n);
32         for(int i = 0; i < n; i++)
33         {
34             scanf("%d%d", &a, &b);
35             st = a;
36             deg[a]++; deg[b]++;
37             G[a][b]++; G[b][a]++;
38         }
39 
40         bool ok = true;
41         for(int i = 1; i <= 50; i++) if(deg[i] % 2) { ok = false; break; }
42         if(!ok) { puts("some beads may be lost"); continue; }
43 
44         Euler(st);
45 
46     }
47 
48     return 0;
49 }