44 lines
1.5 KiB
Python
44 lines
1.5 KiB
Python
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# SPDX-License-Identifier: MIT
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# Copyright (c) 2022 Akumatic
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#
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# https://adventofcode.com/2022/day/9
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def read_file(filename: str = "input.txt") -> list:
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with open(f"{__file__.rstrip('code.py')}{filename}", "r") as f:
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return [(line.split()[0], int(line.split()[1])) for line in f.readlines()]
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def simulate_moves(instructions: list, knots: int) -> int:
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pos = [[0, 0] for _ in range(knots)]
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tail_history = {(0, 0)}
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for dir, steps in instructions:
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for _ in range(steps):
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# head movement
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pos[0][0] += {"R": 1, "L": -1}.get(dir, 0)
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pos[0][1] += {"U": 1, "D": -1}.get(dir, 0)
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# following knots movement
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for i in range(1, knots):
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dx = pos[i-1][0] - pos[i][0]
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dy = pos[i-1][1] - pos[i][1]
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dist = (dx**2 + dy**2)**0.5
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if dist < 2.0:
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continue
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if dist == 2.0:
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pos[i][0] += (dx // 2)
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pos[i][1] += (dy // 2)
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else: # dist > 2.0:
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pos[i][0] += (dx // abs(dx))
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pos[i][1] += (dy // abs(dy))
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tail_history.add((pos[-1][0], pos[-1][1]))
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return len(tail_history)
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def part1(vals: list) -> int:
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return simulate_moves(vals, 2)
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def part2(vals: list) -> int:
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return simulate_moves(vals, 10)
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if __name__ == "__main__":
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vals = read_file()
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print(f"Part 1: {part1(vals)}")
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print(f"Part 2: {part2(vals)}")
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