2021 day 10.

src/holt59/aoc/2021/day10.py

@@ -1,7 +1,47 @@
+from functools import reduce
 from typing import Any, Iterator
 
 from ..base import BaseSolver
 
+BRACKETS = {"{": "}", "[": "]", "<": ">", "(": ")"}
+
+CORRUPT_SCORES = {")": 3, "]": 57, "}": 1197, ">": 25137}
+COMPLETE_SCORES = {")": 1, "]": 2, "}": 3, ">": 4}
+
+
+def corrupted_or_incomplete(line: str) -> tuple[bool, str]:
+    opens: list[str] = []
+
+    for c in line:
+        if c in BRACKETS:
+            opens.append(c)
+        elif BRACKETS[opens[-1]] != c:
+            return True, c
+        else:
+            opens.pop()
+
+    return (False, "".join(opens))
+
 
 class Solver(BaseSolver):
-    def solve(self, input: str) -> Iterator[Any]: ...
+    def solve(self, input: str) -> Iterator[Any]:
+        lines = input.splitlines()
+
+        answer_1: int = 0
+        incomplete_scores: list[int] = []
+
+        for line in lines:
+            c, r = corrupted_or_incomplete(line)
+            if c:
+                answer_1 += CORRUPT_SCORES[r]
+            else:
+                incomplete_scores.append(
+                    reduce(
+                        lambda s, c: s * 5 + COMPLETE_SCORES[BRACKETS[c]],
+                        reversed(r),
+                        0,
+                    ),
+                )
+
+        yield answer_1
+        yield sorted(incomplete_scores)[len(incomplete_scores) // 2]