robot.rb

# File: robot.rb
# Author: Luke Hubbard
# Gist: http://gist.github.com/gists/18289
# License: MIT
# Description: Ruby version of robot to solve Google Treasure Hunt.

def robot(rows, cols)
  matrix = Array.new(rows).collect{ Array.new(cols) }
  x, y = rows-1, cols-1
  x.downto(0) do |row|
    y.downto(0) do |col|
      a = (matrix[row+1][col] unless matrix[row+1].nil?) || 0
      b = matrix[row][col+1] || 0
      sum = a + b
      matrix[row][col] = sum > 0 ? sum : 1
    end
  end
  matrix[0][0]
end
 
start = Time.now
solution = robot(48, 54)
time = Time.now - start
puts "Robot solution #{solution} computed in #{time}s"