（链表）14-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) {
        // 判空链表
        if (head == null) {
            return head;
        }
        // 奇数链表的指针
        ListNode one = head;
        // 偶数链表的指针
        ListNode two = head.next;
        // 临时指针记录偶数链表的头指针-用于最后奇偶相连
        ListNode temp = two;
        while (two != null && two.next != null) {
            one.next = two.next;
            one = two.next;
            two.next = one.next;
            two = one.next;
        }
        // 奇偶链表相连
        one.next = temp;
        // 返回结果
        return head;
    }
}