逆序輸入

 1 #include <stdio.h>
 2 #include <stdlib.h>
 3 #include <malloc.h>
 4 #define maxn 1000
 5 
 6 //鄰接表(點很多，邊較少)
 7 //共有n個點，點編號為1~n，m條邊
 8 //無向圖
 9 
10 struct node
11 {
12     long value;
13     struct node *next;
14 }*d[maxn+1];
15 
16 int main()
17 {
18     struct node *p;
19     long n,m,i,x,y;
 
20     scanf("%ld%ld",&n,&m);
21     for (i=1;i<=n;i++)
22         d[i]=NULL;
23     //點在鏈表的順序與輸入的順序相反
24     for (i=1;i<=m;i++)
25     {
26         scanf("%ld%ld",&x,&y);
27         //to point x
28         ///新創一個內存空間，p指針指向這個內存空間(結構體)
29         p=(struct node *) malloc (sizeof(struct
 
 node));
30         p->value=y;
31         ///p指向的結構體的內部結構體指針next指向d[x](之前的數據)
32         p->next=d[x];
33         ///當前數據在起始指針位置
34         d[x]=p;
35         //to point y
36         //Don‘t forget initialization
37         p=(struct node *) malloc (sizeof(struct node));
38         p->value=x;
39         p->next=d[y];
 
40         d[y]=p;
41     }
42     for (i=1;i<=n;i++)
43     {
44         printf("Point %ld:",i);
45         p=d[i];
46         while (p)
47         {
48             printf(" %ld",p->value);
49             p=p->next;
50         }
51         printf("\n");
52     }
53     return 0;
54 }
55 /*
56 Input:
57 6 9
58 1 2
59 1 3
60 1 4
61 2 5
62 3 4
63 3 5
64 3 6
65 4 6
66 5 6
67 Output:
68 Point 1: 4 3 2
69 Point 2: 5 1
70 Point 3: 6 5 4 1
71 Point 4: 6 3 1
72 Point 5: 6 3 2
73 Point 6: 5 4 3
74 */

正序輸入：

 1 #include <stdio.h>
 2 #include <stdlib.h>
 3 #include <malloc.h>
 4 #define maxn 1000
 5 
 6 //鄰接表(點很多，邊較少)
 7 //共有n個點，點編號為1~n，m條邊
 8 //無向圖
 9 
10 struct node
11 {
12     long value;
13     struct node *next;
14 }*d[maxn+1],*e[maxn+1];
15 
16 int main()
17 {
18     struct node *p;
19     long n,m,i,x,y;
20     scanf("%ld%ld",&n,&m);
21     for (i=1;i<=n;i++)
22     {
23         d[i]=(struct node *) malloc (sizeof(struct node));
24         e[i]=d[i];
25     }
26 
27     //點在鏈表的順序與輸入的順序相反
28     for (i=1;i<=m;i++)
29     {
30         scanf("%ld%ld",&x,&y);
31         //to point x
32         ///新創一個內存空間，p指針指向這個內存空間(結構體)
33         p=(struct node *) malloc (sizeof(struct node));
34         ///在記錄與x相鄰的結點的鏈表的末端加入數值，
35             ///並且末端與一個新的結構體指針連接，使當前末端為一個結構體指針
36         e[x]->value=y;
37         e[x]->next=p;
38         e[x]=p;
39         //to point y
40         //Don‘t forget initialization
41         p=(struct node *) malloc (sizeof(struct node));
42         e[y]->value=x;
43         e[y]->next=p;
44         e[y]=p;
45     }
46     for (i=1;i<=n;i++)
47     {
48         printf("Point %ld:",i);
49         p=d[i];
50         ///末端為一個結構體指針
51         while (p!=e[i])
52         {
53             printf(" %ld",p->value);
54             p=p->next;
55         }
56         printf("\n");
57     }
58     return 0;
59 }
60 /*
61 Input:
62 6 9
63 1 2
64 1 3
65 1 4
66 2 5
67 3 4
68 3 5
69 3 6
70 4 6
71 5 6
72 Output:
73 Point 1: 2 3 4
74 Point 2: 1 5
75 Point 3: 1 4 5 6
76 Point 4: 1 3 6
77 Point 5: 2 3 6
78 Point 6: 3 4 5
79 */

用結構體指針存儲數據__正序_逆序下的輸入