mirror of
https://github.com/TheAlgorithms/Python.git
synced 2024-12-18 09:10:16 +00:00
cbbc43ba3a
* Updated problem_04 in project_euler
* fixup! Format Python code with psf/black push
* That number is larger than our acceptable range.
* updating DIRECTORY.md
Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
Co-authored-by: Christian Clauss <cclauss@me.com>
52 lines
1.4 KiB
Python
52 lines
1.4 KiB
Python
"""
|
|
Problem:
|
|
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 which
|
|
is less than N.
|
|
"""
|
|
|
|
|
|
def solution(n):
|
|
"""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):
|
|
|
|
# converts number into string.
|
|
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__":
|
|
import doctest
|
|
|
|
doctest.testmod()
|
|
|
|
print(solution(int(input().strip())))
|