欧拉路

Fluery算法：

 1 #include <cstdlib>
 2 #include <cstring>
 3 #include <cstdio>
 4 #include <iostream>
 5 #include <algorithm>
 6 using namespace std;
 7 
 8 /*
 9 弗罗莱算法
10 */
11 
12 #define MAXN 1005
13 
14 int stk[MAXN];
15 int top;
16 int N, M, start;
17 int mp[MAXN][MAXN];
18 
19 void dfs(int x) {
20     stk[top++] = x;
21     for (int i = 1; i <= N; ++i) {
22         if (mp[x][i]) {
23             mp[x][i] = mp[i][x] = 0; // 删除此边
24             dfs(i);
25             break;
26         }    
27     }
28 }
29 
30 void fleury(int start) {
31     int brige;
32     top = 0;
33     stk[top++] = start; // 将起点放入Euler路径中
34     while (top > 0) {
35         brige = 0;
36         for (int i = 1; i <= N; ++i) { // 试图搜索一条边不是割边（桥） 
37             if (mp[stk[top-1]][i]) {
38                 brige = 1;
39                 break;
40             }
41         }
42         if (!brige) { // 如果没有点可以扩展，输出并出栈
43             printf("%d ", stk[--top]);
44         } else { // 否则继续搜索欧拉路径
45             dfs(stk[--top]);
46         }
47     }
48     printf("\n");
49 }
50 
51 int main() {
52     int x, y, deg, num;
53     while (scanf("%d %d", &N, &M) != EOF) {
54         memset(mp, 0, sizeof(mp));
55         for (int i = 0; i < M; ++i) {
56             scanf("%d %d", &x, &y);
57             mp[x][y] = mp[y][x] = 1;
58         }
59         start = 1, num = 0;
60         for (int i = 1; i <= N; ++i) {
61             deg = 0;
62             for (int j = 1; j <= N; ++j) {
63                 deg += mp[i][j];    
64             }
65             if (deg % 2 == 1) {
66                 start = i, ++num;
67             }
68         }
69         if (num == 0 || num == 2) fleury(start);
70         else printf("No Euler Path\n");
71     }
72     return 0;    
73 }

 

posted @ 2015-06-14 18:28  Eason Liu  阅读(128)  评论(0)    收藏  举报