Solution to find pivot in linear time

find_pivot.rb

def find_pivot(array)
  	return -1 if array.empty?

	left = 0
	right = array[1..-1].inject(0,:+)

	for i in 0...array.length
		return i if left == right
		left += array[i]
		right -= array[i+1] || 0
	end
	
	return -1
end


p find_pivot([]) == -1
p find_pivot([1]) == 0
p find_pivot([1,1]) == -1
p find_pivot([1,2,1]) == 1
p find_pivot([1,-1,5,4,6,-2,1]) == 3
p find_pivot([0,0]) == 0
p find_pivot([1,0,0,1]) == 1