added 2024/day21

Author: anight

2024/day21/answers.txt

@@ -0,0 +1,2 @@
+162740
+203640915832208

2024/day21/input.txt

@@ -0,0 +1,5 @@
+593A
+283A
+670A
+459A
+279A

2024/day21/run.py

@@ -0,0 +1,138 @@
+#! /usr/bin/env python3
+
+def load_data(filename):
+	with open(filename, 'r') as f:
+		for line in f:
+			line = line.rstrip('\n')
+			yield line
+
+codes = list(load_data('input.txt'))
+
+# Part One
+
+from functools import cache
+from collections import defaultdict, Counter
+
+class Keypad:
+
+	@classmethod
+	@cache
+	def xy(cls, key):
+		for y in range(len(cls.keypad)):
+			if key in cls.keypad[y]:
+				return cls.keypad[y].index(key), y
+		raise Exception(f"Key {key} not found in {cls}")
+
+	@classmethod
+	@cache
+	def paths(cls, from_, to):
+		def is_valid(x, y, path):
+			for step in path:
+				dx, dy = {'<': (-1, 0), '>': (1, 0), '^': (0, -1), 'v': (0, 1)}[step]
+				x += dx
+				y += dy
+				if cls.keypad[y][x] is None:
+					return False
+			return True
+		fx, fy = cls.xy(from_)
+		tx, ty = cls.xy(to)
+		dx = '<' * (fx-tx) if tx < fx else '>' * (tx-fx)
+		dy = '^' * (fy-ty) if ty < fy else 'v' * (ty-fy)
+		return set([dx+dy+'A'] * is_valid(fx, fy, dx+dy) + [dy+dx+'A'] * is_valid(fx, fy, dy+dx))
+
+	@classmethod
+	@cache
+	def shortest_from_to(cls, from_, to, backed):
+		paths = cls.paths(from_, to)
+		if not backed:
+			return next(iter(paths))
+		min_path = min( [DirKeypad.shortest_seq(path, backed-1) for path in paths], key=len )
+		return min_path
+
+	@classmethod
+	@cache
+	def shortest_seq(cls, code, backed):
+		ret = ''
+		current = 'A'
+		for c in code:
+			ret += cls.shortest_from_to(current, c, backed)
+			current = c
+		return ret
+
+
+
+
+
+
+
+
+	@classmethod
+	@cache
+	def shortest_path(cls, from_, to):
+		paths = cls.paths(from_, to)
+		min_path = min( [(DirKeypad.shortest_seq(path, 5), path) for path in paths], key=lambda item: len(item[0]) )[1]
+		return min_path
+
+	@staticmethod
+	def str2tokens(s):
+		assert s[-1] == 'A'
+		return [ t + 'A' for t in s.split('A')[:-1] ]
+
+	@classmethod
+	def str2cnt(cls, s):
+		return Counter(cls.str2tokens(s))
+
+	@staticmethod
+	def length(code):
+		return sum([ len(k) * v for k, v in code.items() ])
+
+	@classmethod
+	@cache
+	def move(cls, key):
+		current = 'A'
+		ret = []
+		for c in key:
+			ret.append(cls.shortest_path(current, c))
+			current = c
+		return ret
+
+	@classmethod
+	def shortest_path_quick(cls, code, backed):
+		if not backed:
+			return cls.length(code)
+		ret = defaultdict(int)
+		for k, v in code.items():
+			for m in DirKeypad.move(k):
+				ret[m] += v
+		return DirKeypad.shortest_path_quick(ret, backed-1)
+
+	@classmethod
+	def shortest_seq_quick(cls, code, backed):
+		code = ''.join(cls.move(code))
+		code = cls.str2cnt(code)
+		return cls.shortest_path_quick(code, backed)
+
+class NumKeypad(Keypad):
+	keypad = [['7', '8', '9'], ['4', '5', '6'], ['1', '2', '3'], [None, '0', 'A']]
+
+class DirKeypad(Keypad):
+	keypad = [[None, '^', 'A'], ['<', 'v', '>']]
+
+def length(code, robots):
+	return len(NumKeypad.shortest_seq(code, robots))
+
+def score(code, robots):
+	return length(code, robots) * int(code[:-1])
+
+result = sum( score(code, 2) for code in codes )
+
+print(result)
+
+# Part Two
+
+def score2(code, robots):
+	return NumKeypad.shortest_seq_quick(code, robots) * int(code[:-1])
+
+result = sum( score2(code, 25) for code in codes )
+
+print(result)

README.md

@@ -9,5 +9,5 @@
 2021 ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ +
 2022 ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ -- ++ ++ -- ++ ++ ++ ++ ++ +
 2023 ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ -- ++ ++ ++ ++ ++ ++ ++ +
-2024 ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ -- ++ ++ ++ +
+2024 ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ +
 ```