Silly little code practice from last week

index.rb

#!/usr/bin/env ruby

# Find the index(es) in an array of integers where sums above and below are equal

def solution(a)
  sum = a.reduce(:+)

  return -1 unless sum
  return 0 if sum - a[0] == 0

  i_sum = 0

  (1...a.size).each do |i|
    i_sum += a[i-1]

    if sum - i_sum - a[i] == i_sum
      return i
    end
  end

  -1
end

puts solution([-1,0,1]*2_000_000)