63 lines
1.9 KiB
Python
63 lines
1.9 KiB
Python
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# SPDX-License-Identifier: MIT
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# Copyright (c) 2020 Akumatic
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#
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#https://adventofcode.com/2020/day/12
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def readFile() -> list:
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with open(f"{__file__.rstrip('code.py')}input.txt", "r") as f:
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return [line.strip() for line in f.readlines()]
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def part1(input: list) -> int:
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x, y = 0, 0
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dirs = ((1,0), (0, 1), (-1, 0), (0, -1))
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idx = 0
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for instruction in input:
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action = instruction[0]
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value = int(instruction[1:])
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if action == "N":
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y += value
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elif action == "S":
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y -= value
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elif action == "E":
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x += value
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elif action == "W":
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x -= value
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elif action == "F":
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x += dirs[idx][0] * value
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y += dirs[idx][1] * value
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else: # action in ("R", "L")
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sig = 1 if action == "L" else -1
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idx = (idx + sig * value // 90) % 4
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return abs(x) + abs(y)
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def part2(input: list) -> int:
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x, y, wx, wy = 0, 0, 10, 1
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dirs = ((1,1), (-1, 1), (-1, -1), (1, -1))
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idx = 0
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for instruction in input:
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action = instruction[0]
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value = int(instruction[1:])
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if action == "N":
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wy += value
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elif action == "S":
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wy -= value
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elif action == "E":
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wx += value
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elif action == "W":
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wx -= value
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elif action == "F":
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x += wx * value
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y += wy * value
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else: # action in ("R", "L")
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sig = 1 if action == "L" else -1
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for _ in range(value // 90):
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idx_prev, idx = idx, (idx + sig) % 4
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tmp_wx = wx
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wx = wy * dirs[idx_prev][1] * dirs[idx][0]
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wy = tmp_wx * dirs[idx_prev][0] * dirs[idx][1]
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return abs(x) + abs(y)
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if __name__ == "__main__":
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input = readFile()
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print(f"Part 1: {part1(input)}")
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print(f"Part 2: {part2(input)}")
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