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来源：互联网发布：暗网8级网络编辑：程序博客网时间：2024/06/01 10:02

5.4

很好玩儿的是，我如果这样写就是错误的。

else if(l1.val == l2.val){                flag.next = l1;                flag = flag.next;                flag.next = l2;                flag = flag.next;                l1 = l1.next;                l2 = l2.next;            }

这个错误找了半天才找到。这是由于flag.next的操作会改变l2链表。

应该在flag操作之前，对原有链表进行操作。

/** * Definition for ListNode. * public class ListNode { *     int val; *     ListNode next; *     ListNode(int val) { *         this.val = val; *         this.next = null; *     } * } */ public class Solution {    /**     * @param ListNode l1 is the head of the linked list     * @param ListNode l2 is the head of the linked list     * @return: ListNode head of linked list     */    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {        // write your code here               if(l1 == null){            return l2;        }        if(l2 == null){            return l1;        }        //把l1 当头结点，在l1 的基础上操作        ListNode head = new ListNode(0);        head.next = null;        ListNode flag = head;        while(l1 != null && l2 != null){            //System.out.println("l1:" + l1.val + ";l2:" + l2.val);            if(l1.val < l2.val){                flag.next = l1;                l1 = l1.next;                flag = flag.next;            }            else if(l1.val == l2.val){                flag.next = l1;                l1 = l1.next;                flag = flag.next;                flag.next = l2;                l2 = l2.next;                flag = flag.next;            }            else {                flag.next = l2;                flag = flag.next;                l2 = l2.next;            }        }        while(l1 != null){            //System.out.println("l1:" + l1.val);            flag.next = l1;            flag = flag.next;            l1 = l1.next;           // System.out.println(l1.val);                    }        while(l2 != null){           // System.out.println("l2:" + l2.val);            flag.next = l2;            l2 = l2.next;            flag = flag.next;        }        return head.next;    }}

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