This is the main method for a ProjectEuler problem that provides a grid of numbers (copied and pasted as a string) and wants to find the maximum product of any four consecutive elements horizontally, vertically, or diagonally. I probably could have written each of the if/then statements in a single line, but executing two lines of code actually …

largestproduct.rb

def largestproduct(nums_as_a_string)
  currentmax = 0
	arry = nums_as_a_string.split("\n")
	arry.map! { |row_as_a_string| row_as_a_string.split.map! { |digit| digit.to_i } }
	0.upto( (arry.length - 1).to_i ) do |row|
		0.upto( (arry[row].length - 1).to_i ) do |col|
			if col <= (arry[row].length - 4) 
				rowprod = arry[row][col]*arry[row][col+1]*arry[row][col+2]*arry[row][col+3]
				currentmax = [currentmax,rowprod].max
			end
			if row <= (arry.length - 4)
				colprod = arry[row][col]*arry[row+1][col]*arry[row+2][col]*arry[row+3][col]
				currentmax = [currentmax,colprod].max
				if col <= arry[row].length - 4
					drprod = arry[row][col]*arry[row+1][col+1]*arry[row+2][col+2]*arry[row+3][col+3]
					currentmax = [currentmax,drprod].max
				end
				if col >=3
					dlprod = arry[row][col]*arry[row+1][col-1]*arry[row+2][col-2]*arry[row+3][col-3]
					currentmax = [currentmax,dlprod].max
				end
			end
		end
	end
	
	currentmax
end