Refactoring

src/Year_2015/P11.py

@@ -39,60 +39,67 @@
 # Given Santa's current password (your puzzle input), what should his next
 # password be?
 
-import re
-from string import ascii_lowercase
 
-with open("files/P11.txt", "r") as f:
-    password = [c for c in f.read().strip()]
+with open("files/P11.txt") as f:
+    password = f.read().strip()
 
-forbidden_chars = {105, 108, 111}
+FORBIDDEN_CHARS = {"i", "o", "l"}
+FORBIDDEN_ASCII = {ord(char) for char in FORBIDDEN_CHARS}
 
 
-def rule_1(chars: list[str]) -> bool:
-    # increasing straight of at least three letters
+def rule_1(password: list[str]) -> bool:
     return any(
-        "".join(chars[i : i + 3]) in ascii_lowercase
-        for i in range(len(chars) - 2)
+        ord(password[i]) + 1 == ord(password[i + 1])
+        and ord(password[i + 1]) + 1 == ord(password[i + 2])
+        for i in range(len(password) - 2)
     )
 
 
-def rule_2(chars: list[str], pos: int) -> list[str]:
-    # try with next letter
-    a = ord(chars[pos]) + 1
-    # not contain the letters i, o, or l
-    if a in forbidden_chars:
-        a += 1
-    # wraps around to a
-    if a > 122:
-        a = 97
-        chars[pos] = chr(a)
-        # change now previous letter also
-        rule_2(chars, pos - 1)
-    else:
-        chars[pos] = chr(a)
-    return chars
+def rule_2(password: list[str]) -> bool:
+    return not any(char in FORBIDDEN_CHARS for char in password)
 
 
-def rule_3(chars: list[str]) -> bool:
-    # at least two different, non-overlapping pairs of letters
-    return bool(re.search(r"(\w)\1.*(\w)\2", "".join(chars)))
+def rule_3(password: list[str]) -> bool:
+    pairs = []
+    index = 0
+    while index < len(password) - 1:
+        if password[index] == password[index + 1]:
+            pairs.append(password[index])
+            index += 2
+        else:
+            index += 1
+    return len(set(pairs)) >= 2
 
 
-def part_1() -> None:
-    new_password = password
-    found = False
-    while not found:
-        new_password = rule_2(new_password, -1)
-        # rule 1
-        if not rule_1(new_password):
-            continue
-        # rule # 3
-        if not rule_3(new_password):
+def is_valid_password(password: list[str]) -> bool:
+    return rule_1(password) and rule_2(password) and rule_3(password)
+
+
+def increment_password(password: list[str]) -> list[str]:
+    updated = password.copy()
+
+    for index in range(len(updated) - 1, -1, -1):
+        next_value = ord(updated[index]) + 1
+
+        while next_value in FORBIDDEN_ASCII:
+            next_value += 1
+
+        if next_value > ord("z"):
+            updated[index] = "a"
             continue
 
-        res = "".join(new_password)
-        print(f"Santa's next password is {res}")
-        found = True
+        updated[index] = chr(next_value)
+        return updated
+
+    raise ValueError("Password overflowed")
+
+
+def guess_password(start_password: str) -> str:
+    password = list(start_password)
+    while True:
+        password = increment_password(password)
+        if is_valid_password(password):
+            return "".join(password)
 
 
 # --- Part Two ---
@@ -101,6 +108,9 @@ def part_1() -> None:
 
 
 if __name__ == "__main__":
-    part_1()
+    first_password = guess_password(password)
+    print(f"Santa's next password is {first_password}")
+
     # Same code again
-    part_1()
+    second_password = guess_password(first_password)
+    print(f"Santa's next password is {second_password}")