selective-array-reversing.md

Selective Array Reversing ^{6 Kyu}

^{LINK TO THE KATA - ALGORITHMS LOGIC ARRAYS}

Description

Given an array, return the reversed version of the array (a different kind of reverse though), you reverse portions of the array, you'll be given a length argument which represents the length of each portion you are to reverse.

E.g

selReverse([1, 2, 3, 4, 5, 6], 2)
//=> [2,1, 4,3, 6,5]

if after reversing some portions of the array and the length of the remaining portion in the array is not up to the length argument, just reverse them.

selReverse([2, 4, 6, 8, 10, 12, 14, 16], 3)
//=> [6,4,2, 12,10,8, 16,14]

selReverse(array, length)

• array - array to reverse
• length - length of each portion to reverse

Note: if the length argument exceeds the array length, reverse all of them, if the length argument is zero do not reverse at all.

Solution

const selReverse = (array, portionLength) => {
  if (portionLength === 0) return array

  const result = []

  for (let i = 0; i < array.length; i += portionLength) {
    const currentPortionReversed = array.slice(i, i + portionLength).reverse()

    result.push(currentPortionReversed)
  }

  return result.flat()
}