# This code is derived from the SOM benchmarks, see AUTHORS.md file.
#
# Copyright (c) 2015-2016 Stefan Marr <git@stefan-marr.de>
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the 'Software'), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.

class Permute < Benchmark
  def initialize
    @count = 0
    @v     = nil
  end

  def benchmark
    @count = 0
    @v = Array.new(6, 0)
    permute(6)
    @count
  end

  def permute(n)
    @count += 1
    if n != 0
      n1 = n - 1
      permute(n1)

      n1.downto(0) do |i|
        swap(n1, i)
        permute(n1)
        swap(n1, i)
      end
    end
  end

  def swap(i, j)
    tmp = @v[i]
    @v[i] = @v[j]
    @v[j] = tmp
  end

  def verify_result(result)
    result == 8660
  end
end
