72 lines
1.9 KiB
Python
72 lines
1.9 KiB
Python
from math import dist
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def solve(input):
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points = []
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for line in open(input):
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x,y = map(int, line.strip().split(","))
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points.append((x,y))
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def areas():
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for p in points:
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for q in points:
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if p != q:
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yield area(p,q)
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print(max(areas()))
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lines = list(zip(points, points[1:]+[points[0]]))
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# keep only vertical lines, and sort so the uppermost point (lowest x coord) is the first of the pair
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lines = [(min(p,q),max(p,q)) for p,q in lines if p[1] != q[1]]
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# sort by y coord
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lines.sort(key=lambda l: (l[0][1],l[1][1],l[0][0],l[1][0]))
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print(lines)
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# we want to know if the rectangle formed by a pair of points
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# is completely contained within the axis-aligned polygon defined
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# by the list of points.
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# we can do that with a scanline algorithm:
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# for each x position in the list of points,
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#
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bounds = {}
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ys = sorted(set(p[1] for l in lines for p in l))
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for y in ys:
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# select lines which intersect with the scanline at y
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mylines = []
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for p,q in lines:
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if p[1] <= y <= q[1]:
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mylines.append(p[0])
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bounds[y] = (min(mylines),max(mylines))
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print(ys)
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print(bounds)
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def inbounds(p,q):
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y0 = min(p[1],q[1])
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y1 = max(p[1],q[1])
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x0 = min(p[0],q[0])
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x1 = max(p[0],q[0])
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#print(y0, y1, ys)
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i = ys.index(y0)
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j = ys.index(y1) + 1
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for y in ys[i:j]:
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if not bounds[y][0] <= x0 <= x1 <= bounds[y][1]:
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return False
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return True
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def areas2():
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for p in points:
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for q in points:
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if p != q and inbounds(p,q):
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yield area(p,q)
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print(max(areas2()))
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def area(p,q):
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dx = abs(p[0] - q[0]) + 1
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dy = abs(p[1] - q[1]) + 1
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return dx*dy
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solve("sample")
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solve("input")
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