1 files changed, 94 insertions, 0 deletions

diff --git a/day3/__init__.py b/day3/__init__.py
new file mode 100644
index 0000000..ebe243e
--- /dev/null
+++ b/day3/__init__.py
@@ -0,0 +1,94 @@
+# -*- coding: utf-8 -*-
+from abc import ABC
+from functools import reduce
+from typing import Optional, Iterator
+
+from aoc import BaseAssignment, I, T
+from aoc.datastructures import Coordinate
+
+
+class Assignment(BaseAssignment, ABC):
+    def symbol_overlap(self, number_coordinates: list[Coordinate], symbols: set[Coordinate]) -> set[Coordinate]:
+        neighbours = {
+            neighbour
+            for coordinate in number_coordinates
+            for neighbour in coordinate.neighbours()
+        }
+
+        return neighbours & symbols
+
+    def read_input(self, example=False) -> tuple[list[str], list[tuple[list[Coordinate], int]], set[Coordinate]]:
+        schematic = list(super().read_input(example))
+        numbers: list[tuple[list[Coordinate], int]] = list()
+        symbols: set[Coordinate] = set()
+
+        for y, row in enumerate(schematic):
+            number: Optional[list[list[Coordinate], str]] = None
+
+            for x, item in enumerate(row):
+                if item.isdigit():
+                    if number is None:
+                        number = [[], '']
+
+                    number[0].append(Coordinate(x, y))
+                    number[1] += item
+                    continue
+
+                if number is not None:
+                    numbers.append((number[0], int(number[1])))
+                    number = None
+
+                if item != '.':
+                    symbols.add(Coordinate(x, y))
+
+            if number is not None:
+                numbers.append((number[0], int(number[1])))
+
+        return schematic, numbers, symbols
+
+
+class AssignmentOne(Assignment):
+    example_result = 4361
+
+    def is_part_number(self, number_coordinates: list[Coordinate], symbols: set[Coordinate]) -> bool:
+        return len(self.symbol_overlap(number_coordinates, symbols)) > 0
+
+    def run(self, input: tuple[list[tuple[list[Coordinate], int]], set[Coordinate]]) -> int:
+        _, numbers, symbols = input
+
+        part_numbers = []
+
+        for coordinates, number in numbers:
+            if self.is_part_number(coordinates, symbols):
+                part_numbers.append(number)
+
+        return sum(part_numbers)
+
+
+class AssignmentTwo(Assignment):
+    example_result = 467835
+
+    def run(self, input: tuple[list[tuple[list[Coordinate], int]], set[Coordinate]]) -> int:
+        schematic, numbers, symbols = input
+
+        possible_gears = {}
+
+        for coordinates, number in numbers:
+            for symbol in self.symbol_overlap(coordinates, symbols):
+                if schematic[symbol.y][symbol.x] != '*':
+                    continue
+
+                if symbol not in possible_gears:
+                    possible_gears[symbol] = []
+
+                possible_gears[symbol].append(number)
+
+        return sum([
+            reduce(
+                lambda total, number: total * number,
+                numbers,
+                1
+            )
+            for symbol, numbers in possible_gears.items()
+            if len(numbers) > 1
+        ])