From a432fa698692c1e6bce0453f55a988b33385d75d Mon Sep 17 00:00:00 2001
From: Tom van der Lee <tom@vanderlee.io>
Date: Wed, 15 Dec 2021 17:20:46 +0100
Subject: Day 15

---
 day15/__init__.py | 138 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 138 insertions(+)
 create mode 100644 day15/__init__.py

(limited to 'day15/__init__.py')

diff --git a/day15/__init__.py b/day15/__init__.py
new file mode 100644
index 0000000..38126fc
--- /dev/null
+++ b/day15/__init__.py
@@ -0,0 +1,138 @@
+import math
+from abc import ABC
+from dataclasses import dataclass
+from typing import List, Tuple, Iterator, TypedDict, Dict
+
+from aoc import BaseAssignment
+from aoc.utils import bold
+
+Coordinate = Tuple[int, int]
+Map = List[List[int]]
+
+@dataclass
+class Score:
+    g_score: float
+    h_score: float
+
+    @property
+    def f_score(self):
+        return self.g_score + self.h_score
+
+class Assignment(BaseAssignment, ABC):
+    def parse_item(self, item: str) -> List[int]:
+        return [int(i) for i in item]
+
+    def read_input(self, example = False) -> Map:
+        return list(super().read_input(example))
+
+    @classmethod
+    def neighbours(cls, field: Map, x: int, y: int) -> Iterator[Coordinate]:
+        for ny in list(range(max(0, y - 1), min(len(field) - 1, y + 1) + 1)):
+            if ny == y:
+                continue
+            yield (x, ny)
+
+        for nx in list(range(max(0, x - 1), min(len(field[0]) - 1, x + 1) + 1)):
+            if nx == x:
+                continue
+            yield (nx, y)
+
+    @classmethod
+    def distance(cls, start: Coordinate, end: Coordinate) -> float:
+        start_x, start_y = start
+        end_x, end_y = end
+
+        dx = end_x - start_x
+        dy = end_y - start_y
+
+        return math.sqrt((dx ** 2) + (dy ** 2))
+
+    @classmethod
+    def gen_path(cls, current: Coordinate, came_from: Dict[Coordinate, Coordinate]) -> List[Coordinate]:
+        path = [current]
+        while current in came_from:
+            current = came_from[current]
+            path.append(current)
+        return list(reversed(path))
+
+    @classmethod
+    def a_star(self, field: Map, start: Coordinate, end: Coordinate) -> List[Coordinate]:
+        open = {start}
+        came_from: Dict[Coordinate, Coordinate] = {}
+
+        scores: Dict[Coordinate, Score] = {
+            start: Score(
+                g_score=0,
+                h_score = self.distance(start, end),
+            )
+        }
+
+        while len(open) > 0:
+            current = sorted(open, key=lambda c: scores[c].f_score)[0]
+            if current == end:
+                return self.gen_path(current, came_from)
+
+            open.remove(current)
+            for neighbour in self.neighbours(field, current[0], current[1]):
+                g_score = scores[current].g_score + field[neighbour[1]][neighbour[0]]
+                neighbour_scores = scores.get(neighbour)
+
+                if neighbour_scores is None or g_score < neighbour_scores.g_score:
+                    came_from[neighbour] = current
+                    neighbour_scores = Score(
+                        g_score=g_score,
+                        h_score=self.distance(neighbour, end)
+                    )
+                    scores[neighbour] = neighbour_scores
+
+                    if neighbour not in open:
+                        open.add(neighbour)
+
+        raise Exception('No Path')
+
+    @classmethod
+    def print_field(cls, field: Map, path: List[Coordinate]):
+        print('', flush=False)
+        for y, row in enumerate(field):
+            print(''.join([ bold(str(i), lambda: (x, y) in path) for x, i in enumerate(row) ]), flush=False)
+        print('', flush=True)
+
+    def run(self, input: Map) -> int:
+        start = (0, 0)
+        end = (len(input[0]) - 1, len(input) - 1)
+
+        path = self.a_star(input, start, end)
+
+        self.print_field(input, path)
+
+        path.remove(start)
+        return sum([
+            input[y][x]
+            for x, y
+            in path
+        ])
+
+class AssignmentOne(Assignment):
+    example_result = 40
+
+class AssignmentTwo(Assignment):
+    example_result =  315
+
+    @classmethod
+    def overflow(self, item):
+        return item - 9 if item > 9 else item
+
+    @classmethod
+    def increase_map(cls, map) -> Map:
+        return [
+            [
+                cls.overflow(item + dx + dy)
+                for dx in range(5)
+                for item in row
+            ]
+            for dy in range(5)
+            for row in map
+        ]
+
+    def read_input(self, example = False) -> Map:
+        return self.increase_map(super().read_input(example))
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