LeetCode - 876(JS, Easy)

876. Middle of the Linked List

난이도: Easy

문제해설

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.

해답

/**
 * Definition for singly-linked list.
 * function ListNode(val, next) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.next = (next===undefined ? null : next)
 * }
 */
/**
 * @param {ListNode} head
 * @return {ListNode}
 */
var middleNode = function(head) {
    let listLength = 0;
    let pointer = head; // Linked List 포인터
    
  	// head의 Node개수 세기
    while(pointer.next != null){
        pointer = pointer.next;
        ++listLength;
    }

    pointer = head;
	// list의 중간지점으로 이동    
  	for(let i = 0; i < listLength / 2; i++){
        pointer = pointer.next;
    }

    return pointer;
};