leetcode-Merge Two Sorted Lists

最新推荐文章于 2021-01-31 11:05:56 发布

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本文提供了一种将两个已排序的链表合并为一个新排序链表的方法。通过比较两个链表的节点值并进行拼接操作，最终返回合并后的链表头节点。此算法适用于升序排列的链表。

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Question：
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.

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Solution：

/**
 * 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* head,*cur;
        if(l1->val >l2->val){
            head = l2;
            l2 = l2->next;
        }
        else{
            head = l1;
            l1 = l1->next;
        }
        cur = head;
        while(l1 != NULL && l2 != NULL){
            if(l1->val > l2->val){
                cur->next = l2;
                cur = l2;
                l2 = l2->next;
            }
            else{
                cur->next = l1;
                cur = l1;
                l1 = l1->next;
            }
        }
        if(l1 == NULL){
            cur->next = l2;
        }
        else{
            cur->next = l1;
        }
        return head;
    }
};