Merge Two Sorted Lists

最新推荐文章于 2025-08-20 09:37:41 发布

ayst123

最新推荐文章于 2025-08-20 09:37:41 发布

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分类专栏： leetcode 文章标签： leetcode

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本文介绍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。使用了类似于归并排序中的合并过程，通过比较两个链表节点的值来决定合并顺序。

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比较简单，自己搞定

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.

分析：和merge sort 里的方法一样

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution:
    # @param two ListNodes
    # @return a ListNode
    def mergeTwoLists(self, l1, l2):
        tra,trb = l1,l2
        trc = ListNode(1000)
        prehead = trc
        while True:
            if tra==None:
                trc.next = trb
                return prehead.next
            if trb==None:
                trc.next = tra
                return prehead.next
            
            if tra.val<=trb.val:
                trc.next = tra
                tra = tra.next
            else:
                trc.next = trb
                trb = trb.next
            trc = trc.next

C++

/**
 * 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) {
        ListNode *tra, *trb, *prehead;
        tra = l1;
        trb = l2;
        ListNode *trc = new ListNode(100);
        prehead = trc;
        while (true){
            if (tra==NULL){
                trc->next = trb;
                return prehead->next;
            }
            if (trb==NULL){
                trc->next = tra;
                return prehead->next;
            }
            
            if (tra->val<=trb->val){
                trc->next = tra;
                trc = tra;
                tra = tra->next;
            }
            else{
                trc->next = trb;
                trc = trb;
                trb = trb->next;
            }
        }
    }
};

语法总结：

1. python里时 True, C++ 里是true

2. C++指针时，最好这么写ListNode *p1,*p2; ListNode *p3 = new ListNode(10);