LeetCode: Merge Two Sorted Lists

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Tingmei

最新推荐文章于 2025-08-12 14:30:08 发布

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分类专栏： C++ 算法文章标签： merge null delete struct function list

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本文详细介绍了如何将两个已排序的单链表合并为一个有序链表，并提供了C++代码实现，包括初始化新链表头节点、遍历比较两个链表节点值并构建新链表的过程。

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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.

两个有序单链表合并。

/**
 * 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) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        if (l1 == NULL && l2 == NULL)
             return NULL;
        ListNode* newHead = new ListNode(0);
        ListNode* newCurrent = newHead;
        ListNode* next1 = l1;
        ListNode* next2 = l2;
        while(l1 != NULL && l2 != NULL)
        {
            if (l1->val < l2->val)
            {
                next1 = l1->next;
                newCurrent->next = l1;
                l1->next = NULL;
                l1 = next1;
            }
            else
            {
                next2 = l2->next;
                newCurrent->next = l2;
                l2->next = NULL;
                l2 = next2;
            }
            newCurrent = newCurrent->next;
        }
        
        if(l1 != NULL)
            newCurrent->next = l1;
            
        else
            newCurrent->next = l2;
        
        newCurrent = newHead;
        newHead = newHead->next;
        delete newCurrent;
        return newHead;
    }
};