Day 13

1 files changed, 87 insertions, 0 deletions

diff --git a/day13/__init__.py b/day13/__init__.py
new file mode 100644
index 0000000..d9fd9f2
--- /dev/null
+++ b/day13/__init__.py
@@ -0,0 +1,87 @@
+# -*- coding: utf-8 -*-
+import json
+from abc import ABC
+from functools import cmp_to_key, reduce
+from typing import Iterator, Any, List, Tuple, Union
+
+from aoc import BaseAssignment
+
+
+Packet = Union[List[int], int, List["Packet"]]
+
+
+class Assignment(BaseAssignment, ABC):
+    def compare_pair(self, pair: Tuple[Packet, Packet]):
+        packet_a, packet_b = pair
+
+        if isinstance(packet_a, int) and isinstance(packet_b, int):
+            diff = packet_b - packet_a
+            return diff / abs(diff) if diff != 0 else 0
+
+        if isinstance(packet_a, list) and isinstance(packet_b, int):
+            packet_b = [packet_b]
+
+        if isinstance(packet_b, list) and isinstance(packet_a, int):
+            packet_a = [packet_a]
+
+        try:
+            for sub_pair in zip(packet_a, packet_b, strict=True):
+                comparison = self.compare_pair(sub_pair)
+
+                if comparison != 0:
+                    return comparison
+        except ValueError:
+            return self.compare_pair((len(packet_a), len(packet_b)))
+
+        return 0
+
+
+class AssignmentOne(Assignment):
+    example_result = 13
+
+    def pairs(self, input: Iterator[str]):
+        while True:
+            yield (json.loads(next(input)), json.loads(next(input)))
+
+            try:
+                next(input)
+            except StopIteration:
+                break
+
+    def run(self, input: Iterator) -> Any:
+        return sum(
+            index
+            for index, pair in enumerate(self.pairs(input), start=1)
+            if self.compare_pair(pair) > 0
+        )
+
+
+class AssignmentTwo(Assignment):
+    example_result = 140
+
+    def packets(self, input: Iterator[str]):
+        for item in input:
+            if item == "":
+                continue
+
+            yield json.loads(item)
+
+    def run(self, input: Iterator) -> Any:
+        packets = sorted(
+            [[[2]], [[6]], *self.packets(input)],
+            key=cmp_to_key(lambda a, b: self.compare_pair((a, b))),
+            reverse=True,
+        )
+
+        return reduce(
+            lambda o, i: o * i,
+            [
+                index
+                for index, packet in enumerate(packets, start=1)
+                if packet
+                in (
+                    [[2]],
+                    [[6]],
+                )
+            ],
+        )