[리트코드] 206. Reverse Linked List - js

1. 문제

https://leetcode.com/problems/reverse-linked-list/

Reverse Linked List - LeetCode

2. 코드

/**
 * 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 reverseList = function(head) {
    if (head === null) return head; // 리스트가 비었을 경우
    
    let current = head; // [1,2,3,4,5]
    let previous = null;
    
    while (current !== null) {
        let temp = current.next; // [2,3,4,5] -> [3,4,5]...
        current.next = previous; // 노드 연결 순서 뒤집기 
        previous = current; // [1] -> [2,1] -> [3,2,1]...
        current = temp; 
    }
    
    return previous;
};