Reverse a linked list.
Have you met this question in a real interview?
Yes
Example
For linked list 1->2->3, the reversed linked list is 3->2->1
Challenge
/**
Reverse it in-place and in one-pass
* Definition for ListNode.
* public class ListNode {
* int val;
* ListNode next;
* ListNode(int val) {
* this.val = val;
* this.next = null;
* }
* }
*/
public class Solution {
/**
* @param head: The head of linked list.
* @return: The new head of reversed linked list.
*/
public ListNode reverse(ListNode head) {
// write your code here
if(head == null) return head;
ListNode pre = null;
while(head != null){
ListNode temp = head.next;
head.next = pre;
pre = head;
head = temp;
}
return pre;
}
}
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