title: leetcode-206-反轉連結清單(java|python)

date: 2019-09-30 13:48:30

categories:

• leetcode

  tags:

• leetcode

leetcode-206-反轉連結清單(java|python)

• 反轉一個單連結清單。

  示例:

  輸入: 1->2->3->4->5->NULL
  輸出: 5->4->3->2->1->NULL
             

• /**
   * Definition for singly-linked list.
   * public class ListNode {
   *     int val;
   *     ListNode next;
   *     ListNode(int x) { val = x; }
   * }
   */
  class Solution {
      public ListNode reverseList(ListNode head) {
          ListNode l1 = null;
          ListNode l2 = head;
          while(l2!=null){
              ListNode l3 = l2.next;
              l2.next = l1;
              l1 = l2;
              l2 = l3;
          }
          return l1;
      }
  }