TapeEquilibrium

gistfile1.rb

def solution(a)
    # write your code in Ruby 1.9.3
    rsum = a.inject(:+)
    lsum = 0
    res  = nil
    
    a.each_with_index do |v, i|
        rsum -= v
        lsum += v
        diff = (lsum - rsum).abs
        res = diff if res.nil? || diff < res
    end
    
    return res
end