Day 10

1 files changed, 91 insertions, 0 deletions

diff --git a/day10/__init__.py b/day10/__init__.py
new file mode 100644
index 0000000..b41ce55
--- /dev/null
+++ b/day10/__init__.py
@@ -0,0 +1,91 @@
+from collections import Counter
+from functools import reduce
+from math import floor
+from typing import List, Iterator
+
+from aoc import BaseAssignment
+
+
+class IncompleteLine(Exception):
+    def __init__(self, missing: List[str]):
+        self.missing = missing
+
+class CorruptedLine(Exception):
+    def __init__(self, got: str, expected: str, *args, **kwargs):
+        self.excpected = expected
+        self.got = got
+
+pairs = {
+    '(': ')',
+    '[': ']',
+    '{': '}',
+    '<': '>',
+}
+
+
+class Assignment(BaseAssignment):
+    @classmethod
+    def parse_line(cls, line: str):
+        stack = []
+        for character in line:
+            if character in pairs:
+                stack.append(character)
+            elif character == pairs[stack[-1]]:
+                stack.pop()
+            else:
+                raise CorruptedLine(character, pairs[stack[-1]])
+
+        if len(stack) > 0:
+            raise IncompleteLine(list(reversed([pairs[c] for c in stack])))
+
+
+class AssignmentOne(Assignment):
+    example_result = 26397
+
+    penalties = {
+        ')': 3,
+        ']': 57,
+        '}': 1197,
+        '>': 25137,
+    }
+
+    def run(self, input: Iterator[str]) -> int:
+        invalid_characters = []
+        for line in input:
+            try:
+                self.parse_line(line)
+            except CorruptedLine as c:
+                invalid_characters.append(c.got)
+            except IncompleteLine:
+                continue
+
+        counter = Counter(invalid_characters)
+
+        return sum(counter[k] * v for k, v in self.penalties.items())
+
+
+class AssignmentTwo(Assignment):
+    example_result = 288957
+
+    penalties = {
+        ')': 1,
+        ']': 2,
+        '}': 3,
+        '>': 4,
+    }
+
+    def run(self, input: Iterator[str]):
+        scores = []
+        for line in input:
+            try:
+                self.parse_line(line)
+            except CorruptedLine:
+                continue
+            except IncompleteLine as c:
+                scores.append(reduce(
+                    lambda out, item: (out * 5) + self.penalties[item],
+                    c.missing,
+                    0
+                ))
+
+        return sorted(scores)[floor(len(scores) / 2)]