面试题24. 反转链表

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  1. func reverseList(head *ListNode) *ListNode {
  2.      var pre *ListNode
  3.      curr := head
  4.      for curr!= nil{
  5.          pre,curr,curr.Next = curr,curr.Next,pre
  6.      }
  7.      return pre
  8. }

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栈思维

每次在头部插入指针，不停迭代头部指针

  1. func reverseList(head *ListNode) *ListNode {
  2.     dummyHead :=&ListNode{
  3.         Val:  -1,
  4.     }
  5.     for head!= nil{
  6.         pre := dummyHead.Next
  7.         next :=head.Next
  8.         dummyHead.Next = head
  9.         head.Next = pre
  10.         head = next
  11.     }
  12.     return dummyHead.Next
  13. }