144 lines
3.6 KiB
Python
144 lines
3.6 KiB
Python
from lib import *
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EXAMPLE = """
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R 6 (#70c710)
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D 5 (#0dc571)
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L 2 (#5713f0)
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D 2 (#d2c081)
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R 2 (#59c680)
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D 2 (#411b91)
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L 5 (#8ceee2)
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U 2 (#caa173)
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L 1 (#1b58a2)
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U 2 (#caa171)
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R 2 (#7807d2)
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U 3 (#a77fa3)
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L 2 (#015232)
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U 2 (#7a21e3)
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"""
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m = {
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"R": Grid2D.E,
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"D": Grid2D.S,
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"L": Grid2D.W,
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"U": Grid2D.N,
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}
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def solve(i: Input, second=False):
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lines = i.lines()
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ins = []
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for l in lines:
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if not l:
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continue
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d, l, c = l.split()
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ins.append((int(l), m[d]))
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c = (0, 0)
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coords: list[tuple[int, int]] = [c]
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for count, d in ins:
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for _ in range(count):
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c = add2(c, d)
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coords.append(c)
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to_visit: list[tuple[int, int]] = [(1, 1)]
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while to_visit:
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c = to_visit.pop()
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for n in [Grid2D.S, Grid2D.E, Grid2D.W, Grid2D.N]:
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nc = add2(c, n)
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if nc not in coords:
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coords.append(nc)
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to_visit.append(nc)
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return len(set(coords))
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def area(ins):
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c = (0, 0)
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corners = []
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for i, (count, d) in enumerate(ins):
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c = (c[0] + count * d[0], c[1] + count * d[1])
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nd = ins[(i + 1) % len(ins)][1]
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if d == nd:
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raise Exception("Dirs should not be equal!")
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# XXX: This mapping only works when going clockwise!
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match d, nd:
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case Grid2D.W, Grid2D.N:
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c_log = (c[0] + 1, c[1])
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case Grid2D.W, Grid2D.S:
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c_log = (c[0] + 1, c[1] + 1)
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case Grid2D.E, Grid2D.N:
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c_log = (c[0], c[1])
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case Grid2D.E, Grid2D.S:
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c_log = (c[0], c[1] + 1)
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case Grid2D.N, Grid2D.E:
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c_log = (c[0], c[1])
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case Grid2D.N, Grid2D.W:
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c_log = (c[0] + 1, c[1])
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case Grid2D.S, Grid2D.E:
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c_log = (c[0], c[1] + 1)
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case Grid2D.S, Grid2D.W:
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c_log = (c[0] + 1, c[1] + 1)
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case d, nd:
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raise Exception(f"Uncoverred {d=} -> {nd=}")
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corners.append(c_log)
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return int(shoelace_area(corners))
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def area2(ins):
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# Solution based on Shoelace area and the idea that the outside area is
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# perimate * 1 // 2, and then +1 (for four quarter corners). All other
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# corners cancel out to zero.
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c = (0, 0)
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corners = []
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perimeter = 0
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for i, (count, d) in enumerate(ins):
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c = (c[0] + count * d[0], c[1] + count * d[1])
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corners.append(c)
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perimeter += count
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return int(shoelace_area(corners)) + perimeter // 2 + 1
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def solve2(i: Input, second=False):
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lines = i.lines()
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ins = []
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for line in lines:
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if not line:
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continue
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_, _, c = line.split()
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c = c.replace("(#", "").replace(")", "")
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d = int(c[:5], 16)
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m = {"0": Grid2D.E, "1": Grid2D.S, "2": Grid2D.W, "3": Grid2D.N}[c[5]]
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ins.append((d, m))
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assert area(ins) == area2(ins)
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return area(ins)
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def debug():
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ins = [
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( 3, Grid2D.S,),
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( 2, Grid2D.E,),
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( 1, Grid2D.N,),
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( 1, Grid2D.E,),
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( 1, Grid2D.N,),
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( 1, Grid2D.W,),
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( 1, Grid2D.N,),
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( 2, Grid2D.W,),
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]
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# Should be 14 but is 2 because it's going counter-clockwise, but mapping
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# only works for clockwise.
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print(area(ins))
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def main():
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DAY_INPUT = "i18.txt"
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print("Example 1:", solve(Input(EXAMPLE)))
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print("Solution 1:", solve(Input(DAY_INPUT)))
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print("Example 2:", solve2(Input(EXAMPLE), True))
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print("Solution 2:", solve2(Input(DAY_INPUT), True))
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return
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if __name__ == "__main__":
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main()
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