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 }