Can you solve this real interview question? Middle of the Linked List - 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:
[https://assets.leetcode.com/uploads/2021/07/23/lc-midlist1.jpg]
Input: head = [1,2,3,4,5] Output: [3,4,5] Explanation: The middle node of the list is node 3.
Example 2:
[https://assets.leetcode.com/uploads/2021/07/23/lc-midlist2.jpg]
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.
# 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]:
slow = head # initilize slow and fast to head
fast = head
while fast is not None and fast.next is not None:
slow = slow.next # iterate slow for only one node at a time
fast = fast.next.next # iterate fast for two node at a time
return slow # if the fast and fast.next reaches None
# know where the slow is found that node will be the middle node