mirror of
https://github.com/TheAlgorithms/Python.git
synced 2024-12-21 02:30:15 +00:00
4700297b3e
* Enable ruff RUF002 rule * Fix --------- Co-authored-by: Christian Clauss <cclauss@me.com>
52 lines
1.4 KiB
Python
52 lines
1.4 KiB
Python
"""
|
|
Project Euler Problem 4: https://projecteuler.net/problem=4
|
|
|
|
Largest palindrome product
|
|
|
|
A palindromic number reads the same both ways. The largest palindrome made
|
|
from the product of two 2-digit numbers is 9009 = 91 x 99.
|
|
|
|
Find the largest palindrome made from the product of two 3-digit numbers.
|
|
|
|
References:
|
|
- https://en.wikipedia.org/wiki/Palindromic_number
|
|
"""
|
|
|
|
|
|
def solution(n: int = 998001) -> int:
|
|
"""
|
|
Returns the largest palindrome made from the product of two 3-digit
|
|
numbers which is less than n.
|
|
|
|
>>> solution(20000)
|
|
19591
|
|
>>> solution(30000)
|
|
29992
|
|
>>> solution(40000)
|
|
39893
|
|
>>> solution(10000)
|
|
Traceback (most recent call last):
|
|
...
|
|
ValueError: That number is larger than our acceptable range.
|
|
"""
|
|
|
|
# fetches the next number
|
|
for number in range(n - 1, 9999, -1):
|
|
str_number = str(number)
|
|
|
|
# checks whether 'str_number' is a palindrome.
|
|
if str_number == str_number[::-1]:
|
|
divisor = 999
|
|
|
|
# if 'number' is a product of two 3-digit numbers
|
|
# then number is the answer otherwise fetch next number.
|
|
while divisor != 99:
|
|
if (number % divisor == 0) and (len(str(number // divisor)) == 3.0):
|
|
return number
|
|
divisor -= 1
|
|
raise ValueError("That number is larger than our acceptable range.")
|
|
|
|
|
|
if __name__ == "__main__":
|
|
print(f"{solution() = }")
|