remove-nth-node-from-end.js

/*
Given the head of a linked list, remove the nth node from the end of the list and return its head.

 

Example 1:

Input: head = [1,2,3,4,5], n = 2
Output: [1,2,3,5]

Example 2:

Input: head = [1], n = 1
Output: []

Example 3:

Input: head = [1,2], n = 1
Output: [1]

*/

var removeNthFromEnd = function (head, n) {
    let dummy = new ListNode()
    dummy.next = head

    let left = dummy
    let right = head

    while (n > 0 && right) {
        right = right.next
        n -= 1
    }

    while (right) {
        left = left.next
        right = right.next
    }

    //remove nth node
    left.next = left.next.next

    return dummy.next
};