62 lines
1.5 KiB
Markdown
62 lines
1.5 KiB
Markdown
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---
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title: "Advent of Code 2021 - Day 13"
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date: 2021-12-14T23:42:45+01:00
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day: 13
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stars: 2
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---
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```python
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import re
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import numpy as np
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pattern_dots = re.compile(r"([0-9]+),([0-9]+)")
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pattern_folds = re.compile(r"fold along ([xy])=([0-9]+)")
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def load():
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with open("../.input/day13") as f:
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dots, folds = f.read().split("\n\n")
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dots = [(int(x), int(y)) for x, y in pattern_dots.findall(dots)]
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matrix = np.zeros((1 + max(y for _, y in dots), 1 + max(x for x, _ in dots)), dtype=bool)
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for x, y in dots:
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matrix[y, x] = True
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return matrix, [(axis, int(offset)) for axis, offset in pattern_folds.findall(folds)]
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def fold(matrix: np.ndarray, axis, offset) -> np.ndarray:
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if axis == "x":
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result = matrix[:, :offset]
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right = np.fliplr(matrix[:, offset+1:])
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if result.shape == right.shape:
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result |= right
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else:
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result[:, -right.shape[1]:] |= right
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else:
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result = matrix[:offset, :]
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bottom = np.flipud(matrix[offset+1:, :])
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if result.shape == bottom.shape:
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result |= bottom
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else:
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result[-bottom.shape[0]:, :] |= bottom
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return result
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def solve1() -> int:
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dots, folds = load()
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return fold(dots, *folds[0]).sum()
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def solve2() -> None:
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dots, folds = load()
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for axis, offset in folds:
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dots = fold(dots, axis, offset)
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[print("".join(line)) for line in np.where(dots, "#", " ")]
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if __name__ == "__main__":
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print(solve1()) # 638
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solve2() # CJCKEBAPB
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```
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