mirror of
https://github.com/TheAlgorithms/Python.git
synced 2024-11-27 23:11:09 +00:00
70 lines
2.1 KiB
Python
70 lines
2.1 KiB
Python
"""
|
|
Project Euler Problem 79: https://projecteuler.net/problem=79
|
|
|
|
Passcode derivation
|
|
|
|
A common security method used for online banking is to ask the user for three
|
|
random characters from a passcode. For example, if the passcode was 531278,
|
|
they may ask for the 2nd, 3rd, and 5th characters; the expected reply would
|
|
be: 317.
|
|
|
|
The text file, keylog.txt, contains fifty successful login attempts.
|
|
|
|
Given that the three characters are always asked for in order, analyse the file
|
|
so as to determine the shortest possible secret passcode of unknown length.
|
|
"""
|
|
import itertools
|
|
from pathlib import Path
|
|
|
|
|
|
def find_secret_passcode(logins: list[str]) -> int:
|
|
"""
|
|
Returns the shortest possible secret passcode of unknown length.
|
|
|
|
>>> find_secret_passcode(["135", "259", "235", "189", "690", "168", "120",
|
|
... "136", "289", "589", "160", "165", "580", "369", "250", "280"])
|
|
12365890
|
|
|
|
>>> find_secret_passcode(["426", "281", "061", "819" "268", "406", "420",
|
|
... "428", "209", "689", "019", "421", "469", "261", "681", "201"])
|
|
4206819
|
|
"""
|
|
|
|
# Split each login by character e.g. '319' -> ('3', '1', '9')
|
|
split_logins = [tuple(login) for login in logins]
|
|
|
|
unique_chars = {char for login in split_logins for char in login}
|
|
|
|
for permutation in itertools.permutations(unique_chars):
|
|
satisfied = True
|
|
for login in logins:
|
|
if not (
|
|
permutation.index(login[0])
|
|
< permutation.index(login[1])
|
|
< permutation.index(login[2])
|
|
):
|
|
satisfied = False
|
|
break
|
|
|
|
if satisfied:
|
|
return int("".join(permutation))
|
|
|
|
raise Exception("Unable to find the secret passcode")
|
|
|
|
|
|
def solution(input_file: str = "keylog.txt") -> int:
|
|
"""
|
|
Returns the shortest possible secret passcode of unknown length
|
|
for successful login attempts given by `input_file` text file.
|
|
|
|
>>> solution("keylog_test.txt")
|
|
6312980
|
|
"""
|
|
logins = Path(__file__).parent.joinpath(input_file).read_text().splitlines()
|
|
|
|
return find_secret_passcode(logins)
|
|
|
|
|
|
if __name__ == "__main__":
|
|
print(f"{solution() = }")
|