func_code: def quicksort(a, p, r):
      if r <= p:
          return
      q = partition(a, p, r)
      quicksort(a, p, q - 1)
      quicksort(a, q + 1, r)
  
  
  def minimum(a):
      quicksort(a, 0, len(a) - 1)
      return a[0]