A function that takes a list and a number. Returns the maximum number that is no larger than def_max.

limited_maximum.py

"""
A function that takes a list and a number. Returns the maximum number that is no larger than def_max.
"""


def bad_definedMax(in_array, def_max):
	"""
	O(N) (not counting the sorting)
	"""

	arr=in_array.copy()
	arr.sort()

	m = float("-inf")
	for i in arr:
		if i > m and i <= def_max:
			m = i

	return m if m != float("-inf") else None

def definedMax(in_array, def_max):
	"""
	O(logN) (not counting the sorting)
	"""
	arr=in_array.copy()
	arr.sort()

	while(len(arr)>1):
		mid = len(arr)//2

		if arr[mid] == def_max:
			return def_max
		elif def_max < arr[mid]:
			arr = arr[:mid]
		elif def_max > arr[mid]:
			arr = arr[mid:]

	if arr[0] <= def_max:
		return arr[0]
	else:
		return None



assert definedMax([1,2,3,4,6,8], 1) == 1
assert definedMax([1,2,3,4,6,8], 2) == 2
assert definedMax([1,2,3,4,6,8], 3) == 3
assert definedMax([1,2,3,4,6,8], 4) == 4
assert definedMax([1,2,3,4,6,8], 5) == 4
assert definedMax([1,2,3,4,6,8], 6) == 6
assert definedMax([1,2,3,4,6,8], 7) == 6
assert definedMax([1,2,3,4,6,8], 8) == 8
assert definedMax([1,2,3,4,6,8], 9) == 8

from random import randint

for _ in range(100000):
	VALUES = (0,100)
	SIZE = (100,200)
	arr = [randint(*VALUES) for i in range(randint(*SIZE))]
	def_max = randint(*VALUES)
	result = definedMax(arr, def_max)
	bad_result = bad_definedMax(arr, def_max)
	print(arr, def_max, result, bad_result, "="*30, sep="\n")
	assert result == bad_result