From f2f95f765c109b19a28fb962ded0df418747a18b Mon Sep 17 00:00:00 2001
From: Thomas Voss <thomasvoss@live.com>
Date: Wed, 15 Dec 2021 22:10:57 +0100
Subject: Add day 15 solutions

---
 2021/15/puzzles.py | 65 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 65 insertions(+)
 create mode 100644 2021/15/puzzles.py

(limited to '2021/15/puzzles.py')

diff --git a/2021/15/puzzles.py b/2021/15/puzzles.py
new file mode 100644
index 0000000..0b294f5
--- /dev/null
+++ b/2021/15/puzzles.py
@@ -0,0 +1,65 @@
+#!/usr/bin/env python3
+
+from heapq import heappop, heappush
+from itertools import product
+from typing import NamedTuple
+
+from libaoc import matrix, read_int_matrix
+
+
+class Node(NamedTuple):
+	x: int
+	y: int
+	r: int
+
+	def __lt__(self, other: tuple[int, int, int]) -> bool:
+		return self.r < other.r
+
+
+def elongate(grid: matrix[int]) -> matrix[int]:
+	ngrid: matrix[int] = []
+	inc = lambda n: 1 if n == 9 else n + 1
+	for p1 in grid:
+		p2 = list(map(inc, p1))
+		p3 = list(map(inc, p2))
+		p4 = list(map(inc, p3))
+		p5 = list(map(inc, p4))
+		ngrid.append(p1 + p2 + p3 + p4 + p5)
+
+	for i, j in product(range(4), range(l := len(grid))):
+		ngrid.append(list(map(inc, ngrid[i * l + j])))
+
+	return ngrid
+
+
+def main() -> None:
+	with open("input", "r", encoding="utf-8") as f:
+		data = read_int_matrix(f)
+
+	# START PART 2
+	data = elongate(data)
+	# END PART 2
+
+	X_UPPER = len(data)
+	Y_UPPER = len(data[0])
+
+	heap = [Node(0, 0, 0)]
+	visited = {(0, 0)}
+
+	while heap:
+		node = heappop(heap)
+		if node.x == X_UPPER - 1 and node.y == Y_UPPER - 1:
+			print(node.r)
+			return
+
+		for dx, dy in ((1, 0), (-1, 0), (0, 1), (0, -1)):
+			xi = node.x + dx
+			yi = node.y + dy
+
+			if 0 <= xi < X_UPPER and 0 <= yi < Y_UPPER and (xi, yi) not in visited:
+				visited.add((xi, yi))
+				heappush(heap, Node(xi, yi, node.r + data[xi][yi]))
+
+
+if __name__ == "__main__":
+	main()
-- 
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