Merge Two Sorted Lists

最新推荐文章于 2022-05-22 13:07:29 发布

原创最新推荐文章于 2022-05-22 13:07:29 发布 · 422 阅读

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CC 4.0 BY-SA版权

本文介绍了如何将两个已排序的链表合并为一个已排序的链表，通过比较链表节点的值进行有序连接。

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Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists.

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode *mergeTwoLists(ListNode *l1, ListNode *l2) {
        if(l1==NULL) return l2;
        if(l2==NULL) return l1;
        ListNode *pre1=NULL,*head=l1;
        while(l1 && l2){
            if(l1->val < l2->val){
                pre1=l1;
                l1=l1->next;
            }else if(l1->val == l2->val){
                ListNode *p= l2->next;
                l2->next = l1->next;
                l1->next = l2;
                pre1=l1;
                l1=l2;
                l2=p;
            }else{
                ListNode *p= l2->next;
                l2->next = l1;
                if(pre1==NULL){
                    pre1=l2;
                    head=l2;
                }else{
                    pre1->next = l2;
                    pre1=l2;
                }
                l2=p;
            }
        }
        if(l2){
            pre1->next = l2;
        }
        return head;
    }
};