剑指Offer14 逆序链表

 /*************************************************************************
     > File Name: 14_ReverseListNode.cpp
     > Author: Juntaran
     > Mail: JuntaranMail@gmail.com
     > Created Time: 2016年08月30日 星期二 15时47分32秒
  ************************************************************************/

 #include <stdio.h>
 #include <malloc.h>

 // 链表结构体
 struct ListNode
 {
     int val;
     struct ListNode* next;
 };

 // 构造链表
 ListNode* createList()
 {
     struct ListNode* head;
     struct ListNode* p;
     struct ListNode* q;
     head = p = (ListNode*)malloc(sizeof(ListNode));
     head->val = ;
     for (int i = ; i <= ; ++i)
     {
         q = (ListNode*)malloc(sizeof(ListNode));
         q->val = i;
         p->next = q;
         p = q;
     }
     p->next = NULL;
     return head;
 }

 // 顺序输出链表
 void PrintList(ListNode* head)
 {
     if (head == NULL)
         return;
     ListNode* temp = head;
     printf("PrintList:\n");
     while (temp != NULL)
     {
         printf("%d ", temp->val);
         temp = temp->next;
     }
     printf("\n");
 }

 // 逆序链表
 ListNode* ReverseList(ListNode* head)
 {
     if (head==NULL || head->next==NULL)
         return head;
     ListNode* fast = head->next;
     ListNode* slow = head;
     slow->next = NULL;
     ListNode* temp;

     while (fast->next != NULL)
     {
         temp = fast->next;
         fast->next = slow;
         slow = fast;
         fast = temp;
     }
     fast->next = slow;
     return fast;
 }

 int main()
 {
     ListNode* test = createList();
     PrintList(test);
     test = ReverseList(test);
     PrintList(test);
     return  ;
 }