1 #include<cstdio>
2 #include<cstring>
3 using namespace std;
4 const unsigned MaxJunc = 45;
5 const unsigned MaxStreet = 1995;
6
7 unsigned graph[MaxJunc][MaxStreet];
8 unsigned stack[MaxStreet];
9 unsigned juncDegree[MaxJunc];
10 bool hasVisited[MaxStreet];
11 unsigned top, maxStreetNo;
12
13 void Euler(int s)
14 {
15 int i;
16 for (i = 1; i <= maxStreetNo; i++){
17 if (graph[s][i] && !hasVisited[i]){
18 hasVisited[i] = true;
19 Euler(graph[s][i]);
20 stack[top++] = i;
21
22 }
23 }
24 }
25
26 int main()
27 {
28 unsigned home;
29 unsigned x, y, z;
30 int i;
31 while (1)
32 {
33 memset(graph, 0, sizeof(unsigned)*MaxJunc*MaxStreet);
34 memset(stack, 0, sizeof(unsigned)*MaxStreet);
35 memset(juncDegree, 0, sizeof(unsigned)*MaxJunc);
36 memset(hasVisited, false, sizeof(bool)*MaxStreet);
37 maxStreetNo = 0;
38 top = 0;
39
40 cin >> x >> y;
41 home = min(x, y);
42 if (x == 0 && y == 0)
43 break;
44 while (x != 0 && y != 0)
45 {
46 cin >> z;
47 graph[x][z] = y;
48 juncDegree[x]++;
49 graph[y][z] = x;
50 juncDegree[y]++;
51 maxStreetNo = max(maxStreetNo, z);
52 cin > x >> y;
53 }
54 for (i = 1; i < MaxJunc;++i)
55 if (juncDegree[i] % 2)
56 break;
57 if (i < MaxJunc)
58 {
59 cout << "Round trip does not exit." << endl;
60 }
61 else
62 {
63 Euler(home);
64 for (i = top - 1; i >= 0; i--)
65 cout << stack[i] << " ";
66 cout << endl;
67 }
68 }
69 return 0;
70 }
