3 files changed, 2116 insertions, 0 deletions

diff --git a/day9/__init__.py b/day9/__init__.py
new file mode 100644
index 0000000..afa44aa
--- /dev/null
+++ b/day9/__init__.py
@@ -0,0 +1,108 @@
+# -*- coding: utf-8 -*-
+from abc import ABC
+from copy import copy
+from dataclasses import dataclass
+from typing import Tuple, Iterator, List
+
+from aoc import BaseAssignment
+
+
+@dataclass
+class Coordinate:
+    x: int
+    y: int
+
+    def __hash__(self):
+        return tuple([self.x, self.y]).__hash__()
+
+    def __sub__(self, other: "Coordinate"):
+        return Coordinate(self.x - other.x, self.y - other.y)
+
+    @property
+    def polarity_x(self):
+        try:
+            return abs(self.x) / self.x
+        except ZeroDivisionError:
+            return 0
+
+    @property
+    def polarity_y(self):
+        try:
+            return abs(self.y) / self.y
+        except ZeroDivisionError:
+            return 0
+
+
+class Assignment(BaseAssignment, ABC):
+    def parse_line(self, item: str) -> Tuple[str, int]:
+        direction, amount = item.split(" ")
+        return direction, int(amount)
+
+    def move(self, direction: str, amount: int):
+        pass
+
+    @staticmethod
+    def next_head(head: Coordinate, direction: str):
+        match direction:
+            case "R":
+                head.x += 1
+            case "L":
+                head.x -= 1
+            case "U":
+                head.y += 1
+            case "D":
+                head.y -= 1
+
+    @staticmethod
+    def next_tail(head: Coordinate, tail: Coordinate):
+        delta = head - tail
+
+        if abs(delta.x) > 1 and delta.y == 0:
+            tail.x += delta.x - delta.polarity_x
+        if abs(delta.x) > 1 and abs(delta.y) == 1:
+            tail.x += delta.x - delta.polarity_x
+            tail.y += delta.y
+        if abs(delta.y > 1) and delta.x == 0:
+            tail.y += delta.y - delta.polarity_y
+        if abs(delta.y) > 1 and abs(delta.x) == 1:
+            tail.y += delta.y - delta.polarity_y
+            tail.x += delta.x
+
+    def tail_positions(self, input: Iterator[str]) -> Iterator[Coordinate]:
+        head = Coordinate(0, 0)
+        tail = Coordinate(0, 0)
+
+        for line in input:
+            direction, amount = self.parse_line(line)
+
+            for _ in range(amount):
+                self.next_head(head, direction)
+                self.next_tail(head, tail)
+                yield tail
+
+
+class AssignmentOne(Assignment):
+    example_result = 13
+
+    def run(self, input: Iterator) -> int:
+        unique_tail_positions = set()
+
+        for position in self.tail_positions(input):
+            unique_tail_positions.add(copy(position))
+
+        print(unique_tail_positions)
+
+        for y in range(5):
+            items = []
+            for x in range(6):
+                if Coordinate(x, y) in unique_tail_positions:
+                    items.append("#")
+                else:
+                    items.append(".")
+            print("".join(items))
+
+        return len(unique_tail_positions)
+
+
+class AssignmentTwo(Assignment):
+    pass
diff --git a/day9/example.txt b/day9/example.txt
new file mode 100644
index 0000000..9874df2
--- /dev/null
+++ b/day9/example.txt
@@ -0,0 +1,8 @@
+R 4
+U 4
+L 3
+D 1
+R 4
+D 1
+L 5
+R 2
diff --git a/day9/input.txt b/day9/input.txt
new file mode 100644
index 0000000..3da93c3
--- /dev/null
+++ b/day9/input.txt
@@ -0,0 +1,2000 @@
+L 2
+U 2
+L 1
+D 1
+U 1
+L 2
+R 2
+D 1
+U 2
+D 1
+R 2
+U 1
+L 2
+D 2
+L 2
+R 2
+L 2
+R 1
+L 2
+D 1
+U 1
+L 2
+U 1
+D 1
+R 2
+L 1
+R 1
+L 2
+U 2
+D 2
+U 1
+D 2
+R 1
+D 1
+R 2
+L 2
+D 1
+L 1
+U 2
+R 2
+L 2
+U 2
+D 1
+U 2
+D 2
+R 1
+U 2
+L 2
+D 2
+U 2
+D 2
+L 2
+R 1
+L 2
+D 2
+U 1
+R 2
+U 2
+L 1
+D 2
+R 2
+L 2
+R 1
+L 2
+D 1
+R 2
+L 2
+R 1
+L 2
+D 1
+U 1
+L 1
+D 1
+R 2
+D 1
+L 1
+D 1
+R 1
+D 1
+U 2
+R 1
+L 1
+U 2
+L 2
+D 2
+L 1
+U 1
+D 1
+L 1
+U 1
+D 1
+U 1
+R 2
+L 2
+U 2
+R 2
+L 2
+D 2
+U 1
+L 1
+R 1
+U 2
+R 1
+D 2
+R 1
+L 2
+R 2
+U 2
+D 2
+R 1
+U 2
+L 2
+R 1
+L 2
+D 3
+L 3
+D 3
+L 3
+U 3
+D 2
+R 2
+D 3
+L 1
+R 2
+D 2
+R 2
+D 3
+U 3
+D 1
+R 2
+D 3
+L 1
+D 1
+L 1
+D 3
+R 2
+U 2
+D 3
+R 2
+U 2