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"""

Problem 112: https://projecteuler.net/problem=112

Working from left-to-right if no digit is exceeded by the digit to its left it is

called an increasing number; for example, 134468.

Similarly if no digit is exceeded by the digit to its right it is called a decreasing

number; for example, 66420.

We shall call a positive integer that is neither increasing nor decreasing a "bouncy"

number, for example, 155349.

Clearly there cannot be any bouncy numbers below one-hundred, but just over half of

the numbers below one-thousand (525) are bouncy. In fact, the least number for which

the proportion of bouncy numbers first reaches 50% is 538.

Surprisingly, bouncy numbers become more and more common and by the time we reach

21780 the proportion of bouncy numbers is equal to 90%.

Find the least number for which the proportion of bouncy numbers is exactly 99%.

"""

def check_bouncy(n: int) -> bool:

"""

Returns True if number is bouncy, False otherwise

>>> check_bouncy(6789)

False

>>> check_bouncy(-12345)

False

>>> check_bouncy(0)

False

>>> check_bouncy(6.74)

Traceback (most recent call last):

...

ValueError: check_bouncy() accepts only integer arguments

>>> check_bouncy(132475)

True

>>> check_bouncy(34)

False

>>> check_bouncy(341)

True

>>> check_bouncy(47)

False

>>> check_bouncy(-12.54)

Traceback (most recent call last):

...

ValueError: check_bouncy() accepts only integer arguments

>>> check_bouncy(-6548)

True

"""

if not isinstance(n, int):

raise ValueError("check_bouncy() accepts only integer arguments")

return "".join(sorted(str(n))) != str(n) and "".join(sorted(str(n)))[::-1] != str(n)

def solution(percent: float = 99) -> int:

"""

Returns the least number for which the proportion of bouncy numbers is

exactly 'percent'

>>> solution(50)

538

>>> solution(90)

21780

>>> solution(80)

4770

>>> solution(105)

Traceback (most recent call last):

...

ValueError: solution() only accepts values from 0 to 100

>>> solution(100.011)

Traceback (most recent call last):

...

ValueError: solution() only accepts values from 0 to 100

"""

if not 0 < percent < 100:

raise ValueError("solution() only accepts values from 0 to 100")

bouncy_num = 0

num = 1

while True:

if check_bouncy(num):

bouncy_num += 1

if (bouncy_num / num) * 100 >= percent:

return num

num += 1

if __name__ == "__main__":

from doctest import testmod

testmod()

print(f"{solution(99)}")

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