[LeetCode] 61. Rotate List

https://leetcode.com/problems/rotate-list/

Rotate List - LeetCode

 

이렇게 풀면 안된다.. 다시 풀어보자.

/**
 * Definition for singly-linked list.
 * function ListNode(val, next) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.next = (next===undefined ? null : next)
 * }
 */
/**
 * @param {ListNode} head
 * @param {number} k
 * @return {ListNode}
 */
var rotateRight = function(head, k) {
    if (!head) return head;
    if (!head.next) return head;
    
    let answer = head;
    let curr = head;
    let count = 0;
    
    while (curr) {
        count++;
        curr = curr.next;
    };
    
    for (let i = 0; i < k % count; i++) {
        answer = rotate(answer);    
    }
    
    return answer;
};

function rotate(node) {
    // node를 받으면 순서를 오른쪽으로 옮겨주는 함수.
    let newNode = node;
    let curr = node;
    const newNext = curr;
    let count = 0;
    
    while (newNode.next) { // 마지막 노드 찾기
        count++;
        newNode = newNode.next;
    }
    
    count--;
    
    while (count) {
        count--;
        curr = curr.next;
    }
    curr.next = null;
    
    newNode.next = newNext;
    return newNode;
}