From: Martin DeMello <martindemello@...>
Date: 2008-09-23T06:26:34+09:00
Subject: Re: One-Liners Mashup (#177 again)

On Mon, Sep 22, 2008 at 2:07 PM, Matthew Moss <matthew.moss@gmail.com> wrote:
> Too many solvers not providing additional problems!
>
> Here's another... Assuming you have an array of numeric data, write a
> method that returns an array of progressive sums. That is:
>
>    prog_sum( [1, 5, 13, -6, 20] ) =>  [1, 6, 19, 13, 33]

def prog_sum(ary)
  ary.inject([0, []]) {|(s, a), i| [s+i, a<<(s+i)]}.last
end

Followon: Given an s-expression, print it out as a tree, where [:a,
:b, :c, :d] is the node with parent a and children b, c and d

[:foo, [:bar, [:baz, :quux], :hello, :world], :done] #=>

foo
| -- bar
|    | -- baz
|    |    | -- quux
|    | -- hello
|    | -- world
| -- done

martin