Odd Even Linked List

oddEvenLinkedList.java

/**
 * 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 oddEvenList(ListNode head) {
        if (head == null || head.next == null || head.next.next == null){
            return head;
        }
        var odd = head;
        var even = head.next;
        var previousEven = new ListNode();
        var evenHead = previousEven;
        while (
            odd != null &&
            even != null
        ){
            odd.next = even.next;
            previousEven.next = even;
            previousEven = previousEven.next;
            if (odd.next == null){
                even = null;
            } else {
                odd = odd.next;
                even = odd.next;
            }
        }
        odd.next = evenHead.next;
        previousEven.next = null;
        return head;
    }
}

LeetCode

Odd Even Linked List

Achievement

The above question was solved by me that beat 100% of the total submissions in terms of runtime.

Submission link