Approach #2 (Recursive) [Accepted]1
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21/**
* Definition for singly-linked list.
* public class ListNode {
* int val;
* ListNode next;
* ListNode() {}
* ListNode(int val) { this.val = val; }
* ListNode(int val, ListNode next) { this.val = val; this.next = next; }
* }
*/
class Solution {
public ListNode reverseList(ListNode head) {
if(head==null||head.next==null){
return head;
}
ListNode p=reverseList(head.next);
head.next.next=head;
head.next=null;
return p;
}
}
Approach #1 (Iterative) [Accepted]1
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12class Solution {
public ListNode reverseList(ListNode head) {
ListNode prev=null,curr=head;
while(curr!=null){
ListNode nextNode=curr.next;
curr.next=prev;
prev=curr;
curr=nextNode;
}
return prev;
}
}