Nc78 reverse linked list

NC78 Reverse a linked list

Reverse a linked list _ Niuke Tiba _ Cattle from (nowcoder.com)

JZ24 Reverse a linked list

Reverse a linked list _ Niuke Tiba _ Cattle from (nowcoder.com)

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//11
// iteration 
import java.util.*;
public class Solution {
    public ListNode ReverseList(ListNode head) {
        if(head==null||head.next==null){
            return head;
        }
        ListNode prev=null;
        ListNode cur=head;
        while(cur!=null){
            ListNode next=cur.next;
            cur.next=prev;
            prev=cur;
            cur=next;
        }
        return prev;
    }
}




// // recursive 
// import java.util.*;
// public class Solution {
//     public ListNode ReverseList(ListNode head) {
//         // Recursion end condition 
//         if(head==null||head.next==null){
//             return head;
//         }
//         ListNode vhead=ReverseList(head.next);
//         // Reverse current level node 
//         head.next.next=head;
//         // The tail node is empty 
//         head.next=null;
//         return vhead;
//     }
// }