gistfile1.ru

def search(arr, t)
  min = 0
  max = arr.count -1
  mid = (max-min)/2
  if arr.count == 0 || (arr.count == 1 && arr[0] != t)
    return -1
  elsif t <= arr[mid]
    return search(arr[0..mid], t)
  else
    return mid + search(arr[mid..-1], t)
  end
end