【链表】21.合并两个有序链表

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#链表 #合并两个有序链表

于 2024-01-02 01:17:37 首次发布

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博客围绕合并两个有序链表展开，介绍了迭代法来解决该问题，还分别给出了Python和Java两种编程语言的实现。

题目

法1：迭代法

Python

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
    def mergeTwoLists(self, list1: Optional[ListNode], list2: Optional[ListNode]) -> Optional[ListNode]:
        dummy = ListNode(-1)
        cur = dummy
        cur1, cur2 = list1, list2
        while cur1 and cur2:
            if cur1.val <= cur2.val:
                cur.next = cur1
                cur1 = cur1.next
            else:
                cur.next = cur2
                cur2 = cur2.next   
            cur = cur.next
        cur.next = cur1 if cur1 else cur2

        return dummy.next

Java

class Solution {
    public ListNode mergeTwoLists(ListNode list1, ListNode list2) {
        if (list1 == null) {
            return list2;
        } else if (list2 == null) {
            return list1;
        }
        ListNode dummy = new ListNode(-1);
        ListNode cur = dummy;
        while (list1 != null && list2 != null) {
            if (list1.val <= list2.val) {
                cur.next = list1;
                list1 = list1.next;
            } else {
                cur.next = list2;
                list2 = list2.next;
            }
            cur = cur.next;
        }

        if (list1 == null) {
            cur.next = list2;
        } else if (list2 == null) {
            cur.next = list1;
        }

        return dummy.next;
    }
}