Add Project Euler problem 79 solution 1

project_euler/problem_079/keylog.txt

@@ -0,0 +1,50 @@
+319
+680
+180
+690
+129
+620
+762
+689
+762
+318
+368
+710
+720
+710
+629
+168
+160
+689
+716
+731
+736
+729
+316
+729
+729
+710
+769
+290
+719
+680
+318
+389
+162
+289
+162
+718
+729
+319
+790
+680
+890
+362
+319
+760
+316
+729
+380
+319
+728
+716

project_euler/problem_079/sol1.py

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+"""
+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
+import os
+
+
+def find_secret_passcode(logins: list[str]) -> int:
+    """
+    Returns the shortest possible secret passcode of unknown length.
+
+    >>> find_secret_passcode(["319", "680", "180", "690", "129", "620", "698",
+    ...     "318", "328", "310", "320", "610", "629", "198", "190", "631"])
+    6312980
+
+    >>> 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))
+            break
+
+    raise Exception("Unable to find the secret passcode")
+
+
+def solution() -> int:
+    """
+    Returns the shortest possible secret passcode of unknown length
+    for successful login attempts given by keylog.txt.
+    """
+    with open(os.path.dirname(__file__) + "/keylog.txt") as file:
+        logins = file.read().splitlines()
+
+    return find_secret_passcode(logins)
+
+
+if __name__ == "__main__":
+    print(f"{solution() = }")