Fleury算法 求欧拉回路

Fleury算法

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <cmath>
 5 #include <algorithm>
 6 #include <climits>
 7 #include <vector>
 8 #include <queue>
 9 #include <cstdlib>
10 #include <string>
11 #include <set>
12 #include <stack>
13 #define LL long long
14 #define pii pair<int,int>
15 #define INF 0x3f3f3f3f
16 using namespace std;
17 const int maxn = 1000;
18 bool e[maxn][maxn];
19 int n,m;
20 stack<int>stk;
21 void dfs(int u){
22     stk.push(u);
23     for(int i = 1; i <= n; i++){
24         if(e[u][i]){
25             e[u][i] = false;
26             e[i][u] = false;
27             dfs(i);
28             break;
29         }
30     }
31 }
32 void Fleury(int x){
33     while(!stk.empty()) stk.pop();
34     stk.push(x);
35     int i;
36     while(!stk.empty()){
37         int u = stk.top();
38         stk.pop();
39         for(i = 1; i <= n; i++)
40             if(e[u][i]) break;
41        if(i <= n) dfs(u); else printf("%d ",u);
42     }
43     puts("");
44 }
45 int main() {
46     int u,v,cnt,degree,st;
47     while(~scanf("%d %d",&n,&m)){
48         memset(e,false,sizeof(e));
49         for(int i = 0; i < m; i++){
50             scanf("%d %d",&u,&v);
51             e[u][v] = e[v][u] = true;
52         }
53         cnt = 0;
54         st = 1;
55         for(int i = 1; i <= n; i++){
56             for(int j = 1,degree = 0; j <= n; j++)
57                 if(e[i][j]) degree++;
58             if(degree&1){
59                 st = i;
60                 cnt++;
61             }
62         }
63         if(cnt == 2 || !cnt) Fleury(st);
64         else puts("No Euler path");
65     }
66     return 0;
67 }