奇偶链表问题

Posted 2022-02-09 Alice_yufeng

/**
 * 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) return null;
        ListNode odd = head, even = head.next, firstEven = even;
        while (even != null && even.next != null)
            odd.next = odd.next.next; //奇数编号指向下一个奇数编号
            even.next = even.next.next;
            odd = odd.next;
            even = even.next;
        
        odd.next = firstEven;//循环结束遍历 odd就是最后一个奇数编号节点，将其next指向第一个偶数编号节点
        return head;