nearest_larger

nearest_larger.rb

def left_match(arr, idx)
  num = arr[idx]
  unless idx.zero?
    (idx - 1).downto(0) do |i|
      return i if arr[i] > num
    end
  end
  nil
end

def right_match(arr, idx)
  num = arr[idx]
  unless (idx == arr.size - 1)
    (idx + 1).upto(arr.size - 1) do |i|
      return i if arr[i] > num
    end
  end
  nil
end

def nearest_larger(arr, idx)
  num = arr[idx]

  left = left_match(arr, idx)
  right = right_match(arr, idx)

  case
  when left.nil? && right.nil? 
    nil
  when left.nil?
    right
  when right.nil?
    left
  when arr[left] <= arr[right]
    left
  when arr[right] < arr[left]
    right
  else
    nil
  end
end