反转链表——剑指offer

Posted 2020-10-03

题目：定义一个函数，输入一个链表的头结点，反转该链表并输出反转后链表的头结点。

代码：

 1 #include<stdio.h>
 2 #include"malloc.h"
 3 typedef struct node
 4 {
 5     struct node *next;
 6     int data;
 7 }*ListNode;
 8 
 9 //尾插法创建链表(不带头结点)
10 ListNode creatrList()
11 {
12     ListNode p = (ListNode)malloc(sizeof(ListNode));
13     ListNode s,q;
14     p ->next = NULL;
15     q = p;
16     int x=0;
17     printf("创建链表，以-1结束：");
18     scanf_s("%d", &x);
19     while (x!=-1)
20     {
21         s = (ListNode)malloc(sizeof(ListNode));
22         s->next = NULL;
23         p->data = x;
24         p->next = s;
25         p = s;
26         scanf_s("%d", &x);
27     }
28     return q;
29 }
30 //反转链表
31 ListNode ReverseList(ListNode pHead)
32 {
33     ListNode prev = NULL;
34     ListNode pNode = pHead;
35     ListNode ReverPHead=NULL;
36     while (pNode != NULL)
37     {
38         ListNode pNext = pNode->next;
39         if (pNext == NULL)
40             ReverPHead = pNode;
41         pNode->next = prev;
42         prev = pNode;
43         pNode = pNext;
44     }
45     printf("%d",ReverPHead->data);
46     return ReverPHead;
47 }
48 
49 int main()
50 {
51     ListNode h,RH;
52     h = creatrList();
53 
54     RH=ReverseList(h);
55     if (RH->next == NULL)
56         printf("链表为空\n");
57     else
58     {
59         RH = RH->next;
60         while (RH != NULL)
61         {
62             printf("%3d", RH->data);
63             RH = RH->next;
64         }
65         printf("\n");
66     }
67     return 0;
68 
69 }
70 /*
71 创建链表，以-1结束：1 2 3 4 5 6 -1
72 6  5  4  3  2  1
73 请按任意键继续. . .
74 
75 创建链表，以-1结束：-1
76 链表为空
77 请按任意键继续. . .
78 
79 创建链表，以-1结束：4 -1
80 4
81 请按任意键继续. . .
82 */

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