POJ 1041 John's trip 无向图的【欧拉回路】路径输出

 1 #include <stdio.h>
 2 #include <string.h>
 3 #include <stdlib.h>
 4 #include <math.h>
 5 #include <iostream>
 6 #include <stack>
 7 #include <queue>
 8 #include <algorithm>
 9 
10 #define ll long long
11 using namespace std;
12 const int INF = 0x3f3f3f3f;
13 const int MAXN = 8000;
14 int vis[2000], indegree[50], map[50][2000], n;
15 stack <int> s;
16 
17 void init(){
18     n = 0;
19     memset(vis, 0, sizeof(vis));
20     memset(map, 0, sizeof(map));//define the relationship between vertex and edge
21     memset(indegree, 0, sizeof(indegree));
22 }
23 
24 int euler(int u){
25     int i;
26     for(i = 1; i <= n; ++i){// n represents edges
27         if(map[u][i] && !vis[i]){
28             vis[i] = 1;
29             euler(map[u][i]);
30             s.push(i);
31         }
32     }
33     return 0;
34 }
35 
36 int main(){
37     int first, i, j, x, y, w;
38     while(cin >> x >> y){
39         if(x == 0 && y == 0)    break;
40         cin >> w;
41         init();
42         map[x][w] = y;
43         map[y][w] = x;
44         ++indegree[x];
45         ++indegree[y];
46         first = x > y ? y : x;//get first vertex , but speacil judge as u casual
47         n = n > w ? n : w;//get numbered largest edge
48         while(true){
49             cin >> x >> y;
50             if(!x && !y)
51                 break;
52             cin >> w;
53             map[x][w] = y;
54             map[y][w] = x;
55             ++indegree[x];
56             ++indegree[y];
57             n = n > w ? n : w;
58         }
59         for(i = 1; i < 45; ++i)//judge if exists solution
60             if(indegree[i] % 2) break;
61         if(i < 45)
62             cout << "Round trip does not exist.\n";
63         else{
64             euler(first);
65             while(!s.empty()){
66                 cout << s.top() << ‘ ‘;
67                 s.pop();
68             }
69             cout << endl;
70         }
71     }
72     return 0;
73 }