add1

add1.rb

# http://blog.jazzychad.net/2012/08/01/array-iteration-problem.html

def add1(arr, val, n)
  range = (0 ... arr.length)
  indexes = n < 0 ? range.reverse_each : range.each
  n = n.zero? ? arr.length : n.abs
  
  indexes.each do |idx|
    if arr[idx] == val
      arr[idx] += 1
      (n -= 1).zero? and break
    end
  end
  
  arr
end

if $0 == __FILE__
  def assert(a) a or fail "failed assertion" end
  assert add1([1,4,1,5,1], 1, 0) == [2,4,2,5,2]
  assert add1([1,4,1,5,1], 1, 2) == [2,4,2,5,1]
  assert add1([1,4,1,5,1], 1, -2) == [1,4,2,5,2]
end