Odd Even Linked List

Description

https://leetcode.com/problems/odd-even-linked-list/description/

Solution

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
class Solution {
    public ListNode oddEvenList(ListNode head) {
        if (head == null || head.next == null) return head;
        ListNode odd = head;
        ListNode even = head.next;
        ListNode traverseOdd = odd;
        ListNode endTraverseOdd = null;
        ListNode traverseEven = even;
        
        while(traverseOdd != null && traverseEven != null) {
            traverseOdd.next = traverseEven.next;
            if(traverseOdd.next == null) break; //break at the end of odd node
            traverseOdd = traverseOdd.next;
            traverseEven.next = traverseOdd.next;
            traverseEven = traverseEven.next;
        }
        
        traverseOdd.next = even;
        
        return odd;
    }
}