2020: d06: ex2: add solution

2020/d06/ex2/ex2.py

@@ -0,0 +1,31 @@
+#!/usr/bin/env python
+
+import sys
+from collections import defaultdict
+from typing import DefaultDict, List, Set
+
+
+def solve(raw: List[str]) -> int:
+    answers: DefaultDict[int, Set[str]] = defaultdict(set)
+    group = 0
+    first = True
+    for line in raw:
+        if line == "":
+            group += 1
+            first = True
+            continue
+        if not first:
+            answers[group] &= {char for char in line}
+        else:
+            answers[group] = {char for char in line}
+        first = False
+    return sum(len(answer) for answer in answers.values())
+
+
+def main() -> None:
+    input = [line.strip() for line in sys.stdin.readlines()]
+    print(solve(input))
+
+
+if __name__ == "__main__":
+    main()