My Advent of Code solutions in Python.
kevinyap.ca/2019/12/going-fast-in-advent-of-code/
advent-of-code
python
Add solution for 2023/18
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+56
2023/day18.py
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2023/day18.py
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import fileinput
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from utils import Point, N, S, E, W
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DIR_MAPPING = {
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'U': N,
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'D': S,
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'L': W,
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'R': E,
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'0': E,
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'1': S,
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'2': W,
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'3': N,
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}
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def discrete_polygon_area(points):
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# Use shoelace formula to compute internal area.
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area = 0
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for a, b in zip(points, points[1:] + [points[0]]):
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area += (b.x + a.x) * (b.y - a.y)
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area = int(abs(area / 2.0))
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# Calculate perimeter.
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perimeter = sum(a.dist_manhattan(b) for a, b in zip(points, points[1:] + [points[0]]))
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# Account for outer perimeter strip in final area computation.
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return area + (perimeter // 2) + 1
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# Parse problem input.
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p1_pos = Point(0, 0)
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p2_pos = Point(0, 0)
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p1_points = [p1_pos]
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p2_points = [p2_pos]
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for line in fileinput.input():
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direction, distance, hex_code = line.split()
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p1_dir = DIR_MAPPING[direction]
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p1_dist = int(distance)
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p2_dir = DIR_MAPPING[hex_code[-2]]
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p2_dist = int(hex_code[2:-2], 16)
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p1_pos += p1_dir * p1_dist
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p2_pos += p2_dir * p2_dist
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p1_points.append(p1_pos)
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p2_points.append(p2_pos)
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# Solve problem.
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print("Part 1:", discrete_polygon_area(p1_points))
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print("Part 2:", discrete_polygon_area(p2_points))