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MiddleOfTheLinkedList.js
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// Source : https://leetcode.com/problems/middle-of-the-linked-list
// Author : Dean Shi
// Date : 2018-08-10
/***************************************************************************************
* 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.
*
* Example 1:
*
* Input: [1,2,3,4,5]
* Output: Node 3 from this list (Serialization: [3,4,5])
* The returned node has value 3. (The judge's serialization of this node is [3,4,5]).
* Note that we returned a ListNode object ans, such that:
* ans.val = 3, ans.next.val = 4, ans.next.next.val = 5, and ans.next.next.next = NULL.
*
* Example 2:
*
* Input: [1,2,3,4,5,6]
* Output: Node 4 from this list (Serialization: [4,5,6])
* Since the list has two middle nodes with values 3 and 4, we return the second one.
*
* Note:
*
* The number of nodes in the given list will be between 1 and 100.
*
***************************************************************************************/
/**
* Definition for singly-linked list.
* function ListNode(val) {
* this.val = val;
* this.next = null;
* }
*/
/**
* @param {ListNode} head
* @return {ListNode}
*/
var middleNode = function(head) {
let fastPt = head
let slowPt = head
while (fastPt && fastPt.next) {
fastPt = fastPt.next.next
slowPt = slowPt.next
}
return slowPt
};