advent-of-code/2024/21/one.py
2024-12-25 12:59:49 +01:00

99 lines
2.7 KiB
Python

#!/usr/bin/env python3
import sys
input_file = sys.argv[1]
with open(input_file) as fd:
lines = [line.rstrip() for line in fd.readlines()]
numeric_keypad = ["789", "456", "123", " 0A"]
directional_keypad = [" ^A", "<v>"]
vec = tuple[int, int]
directions = {
"^": (-1, 0), # ^ North
">": (0, 1), # > East
"v": (1, 0), # v South
"<": (0, -1), # < West
}
directional_keypad_buttons = tuple(directions.keys()) + ("A",)
complexity = int(sys.argv[2])
keypads = [directional_keypad] * complexity + [numeric_keypad]
def but_pos(but: str, keypad: list[str]) -> vec:
for i, line in enumerate(keypad):
if but in line:
return i, line.index(but)
raise IndexError("No such button")
def in_bounds(i: int, j: int, keypad: list[str]) -> bool:
if j not in range(3) or i not in range(len(keypad)):
return False
return keypad[i][j] != " "
last_but = "A"
all_a = [but_pos("A", keypad) for keypad in keypads]
score = 0
for code in lines:
print("Code", code)
topresses = 0
for desir_but in code:
print("Button", desir_but)
all_a[-1] = but_pos(last_but, keypads[-1])
start_poss = tuple(all_a)
all_a[-1] = but_pos(desir_but, keypads[-1])
desir_poss = tuple(all_a)
stack = {start_poss}
seen = set()
presses = 0
while desir_poss not in stack:
# print("Press", presses, stack)
presses += 1
nstack = set()
for poss in stack:
for but in directional_keypad_buttons:
# Find which keypad this will move
k = 0
while but == "A" and k < len(keypads) - 1:
i, j = poss[k]
but = keypads[k][i][j]
k += 1
# Do not press the final keypad
if k == len(keypads) - 1 and but == "A":
continue
# Move
direction = directions[but]
i, j = poss[k]
ii, jj = i + direction[0], j + direction[1]
if not in_bounds(ii, jj, keypads[k]):
continue
# Ensure we haven't been in this state before
state = poss[:k] + ((ii, jj),) + poss[k + 1 :]
if state in seen:
continue
seen.add(state)
# print(" Kept", state)
nstack.add(state)
stack = nstack
topresses += presses + 1
last_but = desir_but
numpart = int("0" + code.replace("A", ""))
print(f"{topresses=} * {numpart=}")
score += topresses * numpart
print(score)