2020: d02: ex2: add solution

2020/d02/ex2/ex2.py

@@ -0,0 +1,43 @@
+#!/usr/bin/env python
+
+import re
+import sys
+from dataclasses import dataclass
+from typing import List
+
+
+@dataclass
+class Policy:
+    min: int
+    max: int
+    letter: str
+
+
+@dataclass
+class Password:
+    policy: Policy
+    password: str
+
+
+def is_valid(pwd: Password) -> bool:
+    min = pwd.password[pwd.policy.min - 1] == pwd.policy.letter
+    max = pwd.password[pwd.policy.max - 1] == pwd.policy.letter
+    return min ^ max
+
+
+def solve(passwords: List[Password]) -> int:
+    return sum(map(is_valid, passwords))
+
+
+def main() -> None:
+    pattern = re.compile("([0-9]+)-([0-9]+) (.): (.+)")
+    input = [
+        Password(Policy(int(m.group(1)), int(m.group(2)), m.group(3)), m.group(4))
+        for m in (pattern.match(line) for line in sys.stdin.readlines())
+        if m
+    ]
+    print(solve(input))
+
+
+if __name__ == "__main__":
+    main()