876. Middle of the Linked List

Middle of the Linked List - LeetCode

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:

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

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


  • code
class Solution {
    public ListNode middleNode(ListNode head) {
        ListNode quick = head;
        while (quick != null && quick.next != null){
            quick = quick.next.next;
            head = head.next;
        }
        return head;
    }
}
  • code
class Solution:
    def middleNode(self, head: Optional[ListNode]) -> Optional[ListNode]:
        quick = head
        while quick and quick.next:
            quick = quick.next.next
            head = head.next
        return head