2022: d02: ex2: add solution

2022/d02/ex2/ex2.py

@@ -0,0 +1,71 @@
+#!/usr/bin/env python
+
+import enum
+import sys
+
+
+class Outcome(enum.IntEnum):
+    Lose = 0
+    Draw = 3
+    Win = 6
+
+    @classmethod
+    def from_input(cls, input: str) -> "Outcome":
+        match input:
+            case "X":
+                return cls.Lose
+            case "Y":
+                return cls.Draw
+            case "Z":
+                return cls.Win
+        assert False  # Sanity check
+
+
+class Choice(enum.IntEnum):
+    Rock = 1
+    Paper = 2
+    Scissors = 3
+
+    @classmethod
+    def from_input(cls, input: str) -> "Choice":
+        match input:
+            case "A":
+                return cls.Rock
+            case "B":
+                return cls.Paper
+            case "C":
+                return cls.Scissors
+        assert False  # Sanity check
+
+
+def score(other: Choice, outcome: Outcome) -> int:
+    def choice() -> Choice:
+        match outcome:
+            case Outcome.Lose:
+                delta = -1
+            case Outcome.Draw:
+                delta = 0
+            case Outcome.Win:
+                delta = 1
+        return Choice((other + delta - 1) % 3 + 1)
+
+    return outcome + choice()
+
+
+Round = tuple[Choice, Outcome]
+
+
+def solve(input: list[Round]) -> int:
+    return sum(map(lambda round: score(*round), input))
+
+
+def main() -> None:
+    input: list[Round] = [
+        (Choice.from_input(round[0]), Outcome.from_input(round[2]))
+        for round in sys.stdin.readlines()
+    ]
+    print(solve(input))
+
+
+if __name__ == "__main__":
+    main()