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https://github.com/thib8956/advent-of-code.git
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47 lines
1.3 KiB
Python
47 lines
1.3 KiB
Python
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def parse_machine(machine):
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btn_a, btn_b, prize = [x.split(": ")[1].split(", ") for x in machine]
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btn_a = [int(x.split("+")[1]) for x in btn_a]
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btn_b = [int(x.split("+")[1]) for x in btn_b]
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prize = [int(x.split("=")[1]) for x in prize]
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return (btn_a, btn_b, prize)
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def solve(btn_a, btn_b, prize, offset=0):
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a_x, a_y = btn_a
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b_x, b_y = btn_b
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p_x, p_y = [p + offset for p in prize]
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# apply Cramer's rule to solve the 2x2 system
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A = (p_x*b_y - p_y*b_x) / (a_x*b_y - a_y*b_x)
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B = (a_x*p_y - a_y*p_x) / (a_x*b_y - a_y*b_x)
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if A.is_integer() and B.is_integer():
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return int(A), int(B)
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return None, None
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def main(content):
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part1 = 0
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part2 = 0
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for machine in content:
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btn_a, btn_b, prize = parse_machine(machine)
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A, B = solve(btn_a, btn_b, prize)
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if A is not None and B is not None:
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part1 += 3*A + B
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A, B = solve(btn_a, btn_b, prize, 10000000000000)
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if A is not None and B is not None:
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part2 += 3*A + B
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print("Part 1: ", part1)
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print("Part 2: ", part2)
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if __name__ == "__main__":
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import sys
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infile = sys.argv[1] if len(sys.argv) > 1 else "example.txt"
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with open(infile) as f:
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content = f.read().split("\n\n")
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content = [x.rstrip().split("\n") for x in content]
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main(content)
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