129 lines
2.9 KiB
Python
129 lines
2.9 KiB
Python
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EXAMPLE = """
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R 4
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U 4
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L 3
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D 1
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R 4
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D 1
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L 5
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R 2
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"""
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def clean(text: str) -> list[str]:
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return list(filter(lambda l: l.strip() != "", text.splitlines()))
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def new_pos(h_pos, t_pos, dir):
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if dir == "R":
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new_h_pos = (h_pos[0] + 1, h_pos[1])
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elif dir == "U":
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new_h_pos = (h_pos[0], h_pos[1] + 1)
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elif dir == "L":
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new_h_pos = (h_pos[0] - 1, h_pos[1])
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elif dir == "D":
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new_h_pos = (h_pos[0], h_pos[1] - 1)
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elif dir == "NONE":
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new_h_pos = (h_pos[0], h_pos[1])
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else:
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raise Exception("Unexpected direction.")
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# xxxxx
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# x---x
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# x-O-x
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# x---x
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# xxxxx
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dx, dy = t_pos[0] - new_h_pos[0], t_pos[1] - new_h_pos[1]
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delta = {
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(-1, -1): (0, 0),
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(-1, 0): (0, 0),
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(-1, 1): (0, 0),
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(0, -1): (0, 0),
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(0, 0): (0, 0),
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(0, 1): (0, 0),
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(1, -1): (0, 0),
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(1, 0): (0, 0),
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(1, 1): (0, 0),
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(-2, 2): (1, -1),
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(-2, 1): (1, -1),
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(-2, 0): (1, 0),
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(-2, -1): (1, 1),
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(-2, -2): (1, 1),
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(2, 2): (-1, -1),
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(2, 1): (-1, -1),
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(2, 0): (-1, 0),
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(2, -1): (-1, 1),
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(2, -2): (-1, 1),
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(-1, 2): (1, -1),
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(-1, -2): (1, 1),
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(0, 2): (0, -1),
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(0, -2): (0, 1),
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(1, 2): (-1, -1),
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(1, -2): (-1, 1),
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}
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dx_, dy_ = delta[(dx, dy)]
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new_t_pos = t_pos[0] + dx_, t_pos[1] + dy_
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# print(f"{h_pos=} {t_pos=} {dir=}")
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# print(f"{new_h_pos=} {dx=} {dy=}")
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# print(f"{new_t_pos=}")
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# print("----")
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return new_t_pos, new_h_pos
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def solve(lines: list[str]):
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pos = set()
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h_pos = (0, 0)
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t_pos = (0, 0)
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pos.add(t_pos)
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for i in range(len(lines)):
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dir, amount = lines[i].split()
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for _ in range(int(amount)):
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t_pos, h_pos = new_pos(h_pos, t_pos, dir)
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pos.add(t_pos)
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# 44:00
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return len(pos)
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EXAMPLE2 = """
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R 5
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U 8
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L 8
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D 3
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R 17
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D 10
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L 25
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U 20
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"""
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def solve2(lines: list[str]):
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vis = set()
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poss = [(0, 0) for _ in range(10)]
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vis.add((0, 0))
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for i in range(len(lines)):
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dir, amount = lines[i].split()
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for _ in range(int(amount)):
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for i in range(len(poss) - 1):
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h_pos = poss[i]
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t_pos = poss[i + 1]
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if i == 0:
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t_pos, h_pos = new_pos(h_pos, t_pos, dir)
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else:
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t_pos, h_pos = new_pos(h_pos, t_pos, "NONE")
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poss[i] = h_pos
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poss[i + 1] = t_pos
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vis.add(poss[-1])
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# 58:00
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return len(vis)
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def main():
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example = clean(EXAMPLE)
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print("Example 1:", solve(example))
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data = clean(open("i9.txt").read())
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print("Solution 1:", solve(data))
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example = clean(EXAMPLE2)
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print("Example 2:", solve2(example))
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data = clean(open("i9.txt").read())
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print("Solution 2:", solve2(data))
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if __name__ == "__main__":
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main()
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