LeetCode 206——反转链表

Seawolf

Code:

1. #include <stdio.h>
   
2. 
   
3. struct Node{
   
4. 
   
5.     int val;
   
6.     struct Node *next;
   
7. 
   
8. };
   
9. 
   
10. struct Node* reverseList(struct Node * hd){
    
11. 
    
12.     struct Node *newHead = NULL;
    
13. 
    
14.     while(hd){
    
15. 
    
16.         struct Node *next = hd->next;//next 为b
    
17. 
    
18.         hd->next = newHead;// a的下一个改成null
    
19. 
    
20.         newHead = hd;// newhead变成 a
    
21. 
    
22.         hd = next;// hd 变成 b
    
23.     }
    
24. 
    
25. 
    
26.     return newHead;
    
27. 
    
28. }
    
29. 
    
30. int main() {
    
31. 
    
32.     struct Node a;
    
33.     struct Node b;
    
34.     struct Node c;
    
35.     struct Node d;
    
36.     struct Node e;
    
37. 
    
38.     a.val = 10;
    
39.     b.val = 20;
    
40.     c.val = 30;
    
41.     d.val = 40;
    
42.     e.val = 50;
    
43. 
    
44.     a.next = &b;
    
45.     b.next = &c;
    
46.     c.next = &d;
    
47.     d.next = &e;
    
48.     e.next = NULL;
    
49. 
    
50.     struct Node *head = &a;
    
51. 
    
52.     while(head){
    
53. 
    
54.         printf("%d\n", head->val);
    
55. 
    
56.         head = head->next;
    
57. 
    
58.     }
    
59. 
    
60.     printf("--------------\n");
    
61. 
    
62.     struct Node *head1 = &a;
    
63. 
    
64.     struct Node *ptr = reverseList(head1);
    
65. 
    
66. 
    
67.     while(ptr){
    
68. 
    
69.         printf("%d\n", ptr->val);
    
70. 
    
71.         ptr = ptr->next;
    
72. 
    
73.     }
    
74. 
    
75.     return 0;
    
76. }

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output:

1. 10
   
2. 20
   
3. 30
   
4. 40
   
5. 50
   
6. --------------
   
7. 50
   
8. 40
   
9. 30
   
10. 20
    
11. 10

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