Middle of the Linked List : Given a non-empty, singly linked list with head node head, return a middle node of linked list. If there are two middle nodes, return the second middle node. https://leetcode.com/explore/challenge/card/30-day-leetcoding-challenge/529/week-2/3290/

LinkedListMiddleNodeFastPointer.java

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
class LinkedListMiddleNodeFastPointer {
    public ListNode middleNode(ListNode head) {
        
        ListNode sizePointer = head;
        ListNode middlePointer = head;
        while(sizePointer != null && sizePointer.next != null) {
            middlePointer = middlePointer.next;
            sizePointer = sizePointer.next.next;
        }
        
        return middlePointer;
    }
}