0054-spiral-matrix.rb

# frozen_string_literal: true

# 54. Spiral Matrix
# https://leetcode.com/problems/spiral-matrix

=begin

Given an m x n matrix, return all elements of the matrix in spiral order.

### Example 1:
Input: matrix = [[1,2,3],[4,5,6],[7,8,9]]
Output: [1,2,3,6,9,8,7,4,5]

### Example 2:
Input: matrix = [[1,2,3,4],[5,6,7,8],[9,10,11,12]]
Output: [1,2,3,4,8,12,11,10,9,5,6,7]

### Constraints:
* m == matrix.length
* n == matrix[i].length
* 1 <= m, n <= 10
* -100 <= matrix[i][j] <= 100

=end

# @param {Integer[][]} matrix
# @return {Integer[]}
def spiral_order(matrix)
  (row = matrix.shift) ? row + spiral_order(matrix.transpose.reverse) : []
end

# **************** #
#       TEST       #
# **************** #

require "test/unit"
class Test_spiral_order < Test::Unit::TestCase
  def test_
    assert_equal [1, 2, 3, 6, 9, 8, 7, 4, 5], spiral_order([[1, 2, 3], [4, 5, 6], [7, 8, 9]])
    assert_equal [1, 2, 3, 4, 8, 12, 11, 10, 9, 5, 6, 7], spiral_order([[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12]])
  end
end