Karate Chop - Take Two

karate_chop_2.rb

def chop(int, array_of_int)
  return -1 if array_of_int.empty?

  @max ||= array_of_int.size - 1
  @min ||= 0
  @mid ||= @max / 2 + @min

  return @mid if int == array_of_int[@mid]

  return -1 if @mid == @max

  if int < array_of_int[@mid]
    @max = @mid
  else
    @min = @mid
  end
  
  chop(int, array_of_int) 
end

karate_chop_test.rb

require './karate_chop_2'
require 'test/unit'

class KarateChopTest < Test::Unit::TestCase
  def test_chop
    assert_equal(-1, chop(3, []))
    assert_equal(-1, chop(3, [1]))
    assert_equal(0,  chop(1, [1]))

    assert_equal(0,  chop(1, [1, 3, 5]))
    assert_equal(1,  chop(3, [1, 3, 5]))
    assert_equal(2,  chop(5, [1, 3, 5]))
    assert_equal(-1, chop(0, [1, 3, 5]))
    assert_equal(-1, chop(2, [1, 3, 5]))
    assert_equal(-1, chop(4, [1, 3, 5]))
    assert_equal(-1, chop(6, [1, 3, 5]))

    assert_equal(0,  chop(1, [1, 3, 5, 7]))
    assert_equal(1,  chop(3, [1, 3, 5, 7]))
    assert_equal(2,  chop(5, [1, 3, 5, 7]))
    assert_equal(3,  chop(7, [1, 3, 5, 7]))
    assert_equal(-1, chop(0, [1, 3, 5, 7]))
    assert_equal(-1, chop(2, [1, 3, 5, 7]))
    assert_equal(-1, chop(4, [1, 3, 5, 7]))
    assert_equal(-1, chop(6, [1, 3, 5, 7]))
    assert_equal(-1, chop(8, [1, 3, 5, 7]))
  end
end