【LeetCode】88. 合并两个有序数组

1 ​​题目​​

2 思想

3 代码

# 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]:
        if list1 is None and list2 is None:
            return None
        elif list1 is None:
            return list2
        elif list2 is None:
            return list1
            
        # step1.找出头结点
        if list1.val <= list2.val:
            head = list1 
            list1 = list1.next
        else:
            head = list2 
            list2 = list2.next
        tail = head # 结果链表的尾节点

        # print(head.val)
        # 当两者都不是空的时候        
        while(list1 and list2):
            if list1.val <= list2.val:
                tail.next = list1
                tail = list1
                list1 = list1.next

            else:
                tail.next = list2
                tail = list2
                list2 = list2.next
        if list1:
            tail.next=list1
        if list2:
            tail.next =list2
        return head