剑指Offer14 逆序链表

Posted 2020-08-05 Juntaran

 1 /*************************************************************************
 2     > File Name: 14_ReverseListNode.cpp
 3     > Author: Juntaran
 4     > Mail: [email protected]
 5     > Created Time: 2016年08月30日 星期二 15时47分32秒
 6  ************************************************************************/
 7 
 8 #include <stdio.h>
 9 #include <malloc.h>
10 
11 // 链表结构体
12 struct ListNode
13 {
14     int val;
15     struct ListNode* next;
16 };
17 
18 // 构造链表
19 ListNode* createList()
20 {
21     struct ListNode* head;
22     struct ListNode* p;
23     struct ListNode* q;
24     head = p = (ListNode*)malloc(sizeof(ListNode));
25     head->val = 0;
26     for (int i = 1; i <= 10; ++i)
27     {
28         q = (ListNode*)malloc(sizeof(ListNode));
29         q->val = i;
30         p->next = q;
31         p = q;
32     }
33     p->next = NULL;
34     return head;
35 }
36 
37 // 顺序输出链表
38 void PrintList(ListNode* head)
39 {
40     if (head == NULL)
41         return;
42     ListNode* temp = head;
43     printf("PrintList:\n");
44     while (temp != NULL)
45     {
46         printf("%d ", temp->val);
47         temp = temp->next;
48     }
49     printf("\n");
50 }
51 
52 // 逆序链表
53 ListNode* ReverseList(ListNode* head)
54 {
55     if (head==NULL || head->next==NULL)
56         return head;
57     ListNode* fast = head->next;
58     ListNode* slow = head;
59     slow->next = NULL;
60     ListNode* temp;
61     
62     while (fast->next != NULL)
63     {
64         temp = fast->next;
65         fast->next = slow;
66         slow = fast;
67         fast = temp;
68     }
69     fast->next = slow;
70     return fast;
71 }
72 
73 int main()
74 {
75     ListNode* test = createList();
76     PrintList(test);
77     test = ReverseList(test);
78     PrintList(test);
79     return  0;
80 }