From: Jab <jborer@...>
Date: 2008-06-20T15:19:22+09:00
Subject: Re: little problem (google hiring puzzle)

I believe this works in O(n). (I believe reverse, and zip are O(n)) It
is very similar to other solutions, but I like the each_with_index
method.

data=[4, 3, 2, 1, 2]
front=[1];
back=[1]
data.each_with_index{|val, index| front[index + 1] = front[index] * val}
data.reverse.each_with_index {|val, index| back[index+1] = back[index] * val}

front.pop
back.pop
data=[]
front.zip(back.reverse){|a, b| data.push a * b}

p data

-jacob