leetcode_206_反转链表

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     struct ListNode *next;
 * };
 */

struct ListNode* reverseList(struct ListNode* head){
  struct ListNode *mHead =
	  (struct ListNode *)malloc(sizeof(struct ListNode));
  mHead->val = 0;
  mHead->next = head;

  struct ListNode *p = mHead->next;
  mHead->next = NULL;
  while (p != NULL)
  {
    struct ListNode *s = p;
    p = p->next;
  
    /* 头部插入 */
    s->next = mHead->next;
    mHead->next = s;
  }

  p = mHead->next;
  free(mHead);
  return p;
}