snail.js

/**
 * Description:
 *
 * Snail Sort
 *
 * Given an n x n array,
 * return the array elements arranged from outermost
 * elements to the middle element, traveling clockwise.
 *
 * array = [[1,2,3],
 *          [4,5,6],
 *          [7,8,9]]
 *
 * snail(array) #=> [1,2,3,6,9,8,7,4,5]
 *
 * For better understanding, please follow the numbers of the next array consecutively:
 *
 * array = [[1,2,3],
 *          [8,9,4],
 *          [7,6,5]]
 *
 * snail(array) #=> [1,2,3,4,5,6,7,8,9]
 *
 * NOTE:
 * The idea is not sort the elements from the lowest value
 * to the highest; the idea is to traverse the 2-d array
 * in a clockwise snailshell pattern.
 *
 * NOTE 2:
 * The 0x0 (empty matrix) is represented as en empty array inside an array [[]].
 *
 * Kata URL: https://www.codewars.com/kata/521c2db8ddc89b9b7a0000c1
 *
 */

snail = function (array) {
  let result = [];
  while (array.length > 0) {
    result = result.concat(array.shift());
    for (let i = 0; i < array.length; i++) {
      result.push(array[i].pop());
    }
    if (array.length > 0) {
      result = result.concat(array.pop().reverse());
    }
    for (let i = array.length - 1; i >= 0; i--) {
      result.push(array[i].shift());
    }
  }
  return result;
};