MonkeyKingElector

monkey_king_elector.rb

require 'minitest/autorun'

class MonkeyKingElector

  def elect(n, m)
    (1..n).to_a.tap { |x| x.delete_at(m % x.size - 1) while x.size > 1 }[0]
  end

end


describe MonkeyKingElector do
  before do
    @elector = MonkeyKingElector.new
  end


  it "should elect #1 when n = 1 and m = 1" do
    @elector.elect(1, 1).must_equal 1
  end

  # n = [1, 2], m = 1
  #
  # [2]
  it "should elect #2 when n = 2 and m = 1" do
    @elector.elect(2, 1).must_equal 2
  end

  # n = [1, 2, 3, 4, 5], m = 7
  # [1, 3, 4, 5]
  # [1, 3, 5]
  # [3, 5]
  # [5]
  it "should elect #5 when n = 5 and m = 7" do
    @elector.elect(5, 7).must_equal 5
  end

  # n = [1, 2, 3, 4, 5, 6, 7], m = 3
  # [1, 2, 4, 5, 6, 7]
  # [1, 2, 5, 6, 7]
  # [1, 2, 6, 7]
  # [1, 2, 7]
  # [1, 2]
  # [2]
  it "should elect #2 when n = 7 and m = 3" do
    @elector.elect(7, 3).must_equal 2
  end
end