LeetCode-206. Reverse Linked List

Reverse a singly linked list.

Example:

Input: 1->2->3->4->5->NULL
Output: 5->4->3->2->1->NULL

Follow up:

A linked list can be reversed either iteratively or recursively. Could you implement both?

题解：

class Solution {
public:
  ListNode* reverseList(ListNode* head) {
    ListNode *pre = NULL, *cur = head;
    while (head != NULL) {
        cur = head;
        head = head->next;
        cur->next = pre;
        pre = cur;
    }
    return cur;
  }
};