725. Split Linked List in Parts

https://leetcode.com/problems/split-linked-list-in-parts/

JavaScript

/**
 * Definition for singly-linked list.
 * function ListNode(val) {
 *     this.val = val;
 *     this.next = null;
 * }
 */
/**
 * @param {ListNode} root
 * @param {number} k
 * @return {ListNode[]}
 */
var splitListToParts = function(root, k) {
    let size = 0
    let current = root
    while (current) {
        size += 1
        current = current.next
    }

    let count = size > k ? (size / k) >> 0 : 1
    let extra = size > k ? size % k : 0

    current = root
    let results = []

    while (k > 0) {
        let length = count
        if (extra) {
            length += 1
            extra -= 1
        }

        let start = null
        let end = null

        for (let i = length; i > 0; i--) {
            if (!current) {
                break
            }
            if (!start) {
                start = end = current
            } else {
                end.next = current
                end = end.next
            }

            current = current.next
        }

        if (end) {
            end.next = null
        }

        results.push(start)
        start = null
        k -= 1
    }

    return results
};