From: ex <exeQtor@...>
Date: 2008-06-16T01:59:22+09:00
Subject: little problem (google hiring puzzle)

Hi guys, I wonder if someone can find a pure ruby solution instead of
mine (I still can get out of my *loop* mind):

################################################################################
#	There is an array A[N] of N integers. You have to compose an array
#	Output[N] such that Output[i] will be equal to the product of all
#	the elements of A[] except A[i].
#
#    Example:
#        INPUT:[4, 3, 2, 1, 2]
#        OUTPUT:[12, 16, 24, 48, 24]
#
#    Note: Solve it without the division operator and in O(n).
#===============================================================================

vals = [4, 3, 2, 1, 2]

front = []
back = []
mf = 1
mb = 1
for k in 0...vals.length
	front.push(mf)
	back.unshift(mb)
	mf *= vals[k]
	mb *= vals[vals.length - 1 - k]
end

ans = []
front.each_index{|k| ans.push(front[k]*back[k]) }

p vals
p ans