第五章 图的遍历（深度遍历，广度遍历，城市地图，最少转机）

深度和广度优先搜索：
单词分解：首先是搜索
               深度和广度：是针对图的遍历而言的
图：由顶点和边组成
图的遍历：把图中每一个顶点都访问一次
一：
输入：
5 5（顶点数，边数）
1 2
1 3
1 5
2 4
3 5
输出：
1 2 4 3 5
（按时间戳输出）深度遍历
1 2 3 5 4
（按时间戳输出）广度遍历
 1 #include <stdio.h>
 2 int map[10][10], book[10], n, m,sum;
 3 void dfs(int cur)
 4 {
 5     int i;
 6     printf("%d ",cur);
 7     sum++;
 8     if (sum == n)
 9         return;
10     for (i = 1;i <= n;i++)
11     {
12         if (book[i] == 0 && map[i][cur])
13         {
14             book[i] = 1;
15             dfs(i);
16         }
17     }
18     return;
19 }
20 void bfs(int front)
21 {
22     int que[100];
23     int head = 0, tail = 0;
24     int i;
25     que[tail++] = front;
26     book[front] = 1;
27     while (head < tail)
28     {
29         for (i = 1;i <= n;i++)
30         {
31             if (map[que[head]][i] && book[i]==0)
32             {
33                 book[i] = 1;
34                 que[tail++] = i;
35             }
36         }
37         head++;
38     }
39     for (i = 0;i < tail;i++)
40         printf("%d ",que[i]);
41     printf("\n");
42 }
43 int main()
44 {
45     int x, y,i;
46     scanf("%d%d",&n,&m);
47     for (i = 1;i <= m;i++)
48     {
49         scanf("%d%d",&x,&y);
50         map[x][y] = 1;
51         map[y][x] = 1;
52     }
53     /*book[1] = 1;
54     dfs(1);
55     printf("\n");*/
56     bfs(1);
57     return 0;
58 }
View Code
二：城市地图    
输入（5个顶点，8条边）：
5 8
1 2 2
1 5 10
2 3 3
2 5 7
3 1 4
3 4 4
4 5 5
5 3 3
输出：
9
（从城市1到城市5的最短距离）
 1 #include <stdio.h>
 2 int map[10][10], book[10], n;
 3 int min = 99999;
 4 void dfs(int cur,int sum)
 5 {
 6     int i;
 7     if (min < sum)
 8         return;
 9     if (cur == n)
10     {
11         if (min > sum)
12             min = sum;
13         return;
14     }
15     for (i = 1;i <= n;i++)
16     {
17         if (book[i] == 0 && map[i][cur])
18         {
19             book[i] = 1;
20             dfs(i, sum + map[i][cur]);
21             book[i] = 0;
22         }
23     }
24     return;
25 }
26 int main()
27 {
28     int e,i,x,y,t;
29     scanf("%d%d",&n,&e);
30     for (i = 1;i <= n;i++)
31     {
32         scanf("%d%d%d", &x, &y, &t);
33         map[x][y] = t;
34         map[y][x] = t;
35     }
36     book[1] = 1;
37     dfs(1,0);
38     printf("%d\n",min);
39 
40     return 0;
41 }
View Code
三：最少转机（图的广度优先遍历，最早到达目标城市时，结束）
 1 #include <stdio.h>
 2 int map[10][10], book[10], total;
 3 int n, m, s, e;
 4 struct node
 5 {
 6     int city;
 7     int trans;
 8 };
 9 void bfs()
10 {
11     int head=0, tail=0,i;
12     int flag = 0;
13     struct node que[100];
14     que[tail].city = s;
15     que[tail].trans = 0;
16     book[s] = 1;
17     tail++;
18     while (head < tail)
19     {
20         for (i = 1;i <= n;i++)
21         {
22             if (book[i] == 0 && map[i][que[head].city])
23             {
24                 book[i] = 1;
25                 que[tail].city = i;
26                 que[tail].trans = que[head].trans + 1;
27                 tail++;
28             }
29             if (que[tail].city == e)
30             {
31                 flag = 1;
32                 break;
33             }
34         }
35         if (flag)
36             break;
37         head++;
38     }
39     printf("%d\n",que[tail-1].trans);
40 }
41 int main()
42 {
43     int i,x,y;
44     scanf("%d%d%d%d",&n,&m,&s,&e);
45     for (i = 1;i <= m;i++)
46     {
47         scanf("%d%d",&x,&y);
48         map[x][y] = 1;
49         map[y][x] = 1;
50     }
51     bfs();
52     return 0;
53 }
View Code

 

posted @ 2017-06-24 12:13  daisy_ding  阅读(349)  评论(0)    收藏  举报