LeetCode 876. Middle of the Linked List

Question

Given the head of a singly linked list, return the middle node of the linked list.

If there are two middle nodes, return the second middle node.

 

Example 1:

876ex1 
Input: head = [1,2,3,4,5]
Output: [3,4,5]
Explanation: The middle node of the list is node 3.

 

Example 2:

876ex2 
Input: head = [1,2,3,4,5,6]
Output: [4,5,6]
Explanation: Since the list has two middle nodes with values 3 and 4, we return the second one.

 

Constraints:

  • The number of nodes in the list is in the range [1, 100].
  • 1 <= Node.val <= 100

 

 

Solution

Python

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
    def middleNode(self, head: Optional[ListNode]) -> Optional[ListNode]:
        lst = []
        counts = 0
        while head != None:
            counts += 1
            
            lst.append(head)
            head = head.next
        return lst[counts // 2 ]

Java