Jake Pullen
86 lines
3.5 KiB
Python
86 lines
3.5 KiB
Python
with open(r'advent_of_code\2023\12\input.txt', 'r') as file:
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input = file.readlines()
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test_input = '''???.### 1,1,3
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.??..??...?##. 1,1,3
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?#?#?#?#?#?#?#? 1,3,1,6
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????.#...#... 4,1,1
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????.######..#####. 1,6,5
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?###???????? 3,2,1'''
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test_input = test_input.split('\n')
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#input = test_input
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# Initialize the total number of arrangements
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total_arrangements = 0
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# Dictionary for memoization
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memo = {}
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def count_arrangements(springs:str, blocks:list, spring_index:int, block_index:int, current_block_length:int) -> int:
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"""
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This function calculates the number of valid arrangements of springs and blocks.
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Parameters:
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springs (str): A string of characters, each of which is either '.', '#' or '?'.
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blocks (list): A list of integers representing the blocks.
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spring_index (int): The current index in `springs`.
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block_index (int): The current index in `blocks`.
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current_block_length (int): The current number of consecutive '#' characters.
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Returns:
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int: The number of valid arrangements for the current state.
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"""
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# Create a key for the current state
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state_key = (spring_index, block_index, current_block_length)
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# If the result for the current state is already computed, return it
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if state_key in memo:
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return memo[state_key]
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# If all springs are processed
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if spring_index == len(springs):
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# If all blocks are used and there's no current block, or the last block is of correct size
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if (block_index == len(blocks) and current_block_length == 0) or \
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(block_index == len(blocks) - 1 and blocks[block_index] == current_block_length):
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return 1
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else:
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return 0
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# Initialize the number of arrangements for the current state
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arrangements = 0
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# Try both possibilities for the current spring ('.' or '#')
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for spring in ['.', '#']:
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# If the current spring can be the current possibility
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if springs[spring_index] == spring or springs[spring_index] == '?':
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# If the current spring is '.' and there's no current block
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if spring == '.' and current_block_length == 0:
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arrangements += count_arrangements(springs, blocks, spring_index + 1, block_index, 0)
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# If the current spring is '.' and the current block is of correct size
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elif spring == '.' and current_block_length > 0 and block_index < len(blocks) and blocks[block_index] == current_block_length:
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arrangements += count_arrangements(springs, blocks, spring_index + 1, block_index + 1, 0)
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# If the current spring is '#'
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elif spring == '#':
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arrangements += count_arrangements(springs, blocks, spring_index + 1, block_index, current_block_length + 1)
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# Store the result for the current state in the memoization dictionary
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memo[state_key] = arrangements
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# Return the number of arrangements for the current state
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return arrangements
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# Process each line in the input
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for line in input:
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# Split the line into springs and blocks
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springs, blocks_string = line.split()
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# Convert the blocks string into a list of integers
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blocks = [int(x) for x in blocks_string.split(',')]
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# Clear the memoization dictionary
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memo.clear()
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# Calculate the number of arrangements for the current line
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line_arrangements = count_arrangements(springs, blocks, 0, 0, 0)
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# Add the number of arrangements for the current line to the total number of arrangements
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total_arrangements += line_arrangements
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# Print the total number of arrangements
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print(total_arrangements) |