81 lines
2.3 KiB
Python
81 lines
2.3 KiB
Python
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from functools import lru_cache
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@lru_cache
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def score(serial, x, y):
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# Find the fuel cell's rack ID, which is its X coordinate plus 10.
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# Begin with a power level of the rack ID times the Y coordinate.
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# Increase the power level by the value of the grid serial number (your puzzle input).
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# Set the power level to itself multiplied by the rack ID.
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# Keep only the hundreds digit of the power level (so 12345 becomes 3; numbers with no hundreds digit become 0).
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# Subtract 5 from the power level.
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rack_id = x + 10
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power_level = rack_id * y
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power_level += serial
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power_level *= rack_id
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try:
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return int(str(power_level)[-3]) - 5
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except IndexError:
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return -5
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def part_1(data):
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v = int(data.strip())
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max_val = 0
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max_coord = None
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assert score(8, 3, 5) == 4
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assert score(57, 122, 79) == -5
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assert score(39, 217, 196) == 0
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for x in range(1, 299):
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for y in range(1, 299):
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s = 0
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for x2 in range(x, x + 3):
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for y2 in range(y, y + 3):
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s += score(v, x2, y2)
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if x2 > 300 or y2 > 300:
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assert False
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if s > max_val:
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max_val = s
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max_coord = (x, y)
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assert max_coord is not None
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print(",".join(list(map(str, max_coord))))
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def part_2(data):
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v = int(data.strip())
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max_val = 0
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max_coord = None
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# brute force, just tried if 15 is small enough
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for size in range(2, 15):
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for x in range(1, 299):
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for y in range(1, 299):
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s = 0
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if x + size > 300 or y + size > 300:
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break
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for x2 in range(x, x + size):
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for y2 in range(y, y + size):
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s += score(v, x2, y2)
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if x2 > 300 or y2 > 300:
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assert False
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if s > max_val:
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max_val = s
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max_coord = (x, y, size)
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assert max_coord is not None
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print(",".join(list(map(str, max_coord))))
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def main():
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input_file = __file__.replace(".py", ".txt")
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with open(input_file) as f:
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data = f.read()
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part_1(data)
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part_2(data)
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if __name__ == "__main__":
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main()
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