题解 | 链表的奇偶重排

import java.util.*;

/*
 * public class ListNode {
 *   int val;
 *   ListNode next = null;
 *   public ListNode(int val) {
 *     this.val = val;
 *   }
 * }
 */

public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param head ListNode类 
     * @return ListNode类
     */
    public ListNode oddEvenList (ListNode head) {
            if(head == null || head.next == null){
                return head;
            }

            ListNode odd = head;
            ListNode even = head.next;
            ListNode evenHead = even;


            while(even != null && even.next != null){
                odd.next = even.next;
                odd = odd.next;

                even.next = odd.next;
                even = even.next;
            }
            odd.next = evenHead;
            return head;
        }
}