mirror of
https://github.com/Threnklyn/advent-of-code-go.git
synced 2026-05-18 19:13:27 +02:00
alexchao26
61 lines
1.6 KiB
Python
61 lines
1.6 KiB
Python
def day7(input: str, part: int) -> int:
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ans: int = 0
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lines = input.splitlines()
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for line in lines:
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parts = line.split(": ")
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target = int(parts[0])
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nums = [int(x) for x in parts[1].split(" ")]
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if recurse(part, nums, target, 0, 0):
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ans += target
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return ans
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# brute force all the combinations and return True early if the target is made using all elements of nums array
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def recurse(part: int, nums: list[int], target: int, current: int, index: int) -> bool:
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if target < current:
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return False
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if index == len(nums) and current == target:
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return True
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if index == len(nums) and current != target:
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return False
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if index == 0:
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current = 1
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multiply_result = recurse(part, nums, target, current * nums[index], index + 1)
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if multiply_result:
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return True
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# attempt concatenation operation for part 2
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if part == 2:
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concat_num = int(str(current) + str(nums[index]))
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concat_result = recurse(part, nums, target, concat_num, index + 1)
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if concat_result:
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return True
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if index == 0:
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current = 0
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return recurse(part, nums, target, current + nums[index], index + 1)
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example = """190: 10 19
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3267: 81 40 27
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83: 17 5
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156: 15 6
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7290: 6 8 6 15
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161011: 16 10 13
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192: 17 8 14
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21037: 9 7 18 13
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292: 11 6 16 20"""
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input = open("input.txt").read()
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print(f"part1 example: {day7(example,1)} want 3749")
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print(f"part1: {day7(input,1)} want 66343330034722")
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print(f"part2 example: {day7(example,2)} want 11387")
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print(f"part2: {day7(input,2)} want 637696070419031") # a bit slow but not bad
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