aoc2022/d15.py

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2023-12-09 15:56:22 +01:00
import lib
import math
EXAMPLE = """
Sensor at x=2, y=18: closest beacon is at x=-2, y=15
Sensor at x=9, y=16: closest beacon is at x=10, y=16
Sensor at x=13, y=2: closest beacon is at x=15, y=3
Sensor at x=12, y=14: closest beacon is at x=10, y=16
Sensor at x=10, y=20: closest beacon is at x=10, y=16
Sensor at x=14, y=17: closest beacon is at x=10, y=16
Sensor at x=8, y=7: closest beacon is at x=2, y=10
Sensor at x=2, y=0: closest beacon is at x=2, y=10
Sensor at x=0, y=11: closest beacon is at x=2, y=10
Sensor at x=20, y=14: closest beacon is at x=25, y=17
Sensor at x=17, y=20: closest beacon is at x=21, y=22
Sensor at x=16, y=7: closest beacon is at x=15, y=3
Sensor at x=14, y=3: closest beacon is at x=15, y=3
Sensor at x=20, y=1: closest beacon is at x=15, y=3
"""
def unify_ranges(ranges):
# aaaaaaaaaaa
# bbbb
#
# aaa
# bbb
#
# aaa
# bbb
ranges = sorted(ranges)
while True:
for i in range(len(ranges) - 1):
a, b = ranges[i], ranges[i + 1]
if a == b:
del ranges[i]
break
elif a[0] == b[0]:
ranges[i] = (a[0], max(a[1], b[1]))
del ranges[i + 1]
break
elif a[1] == b[1]:
ranges[i] = (min(a[0], b[0]), b[1])
del ranges[i + 1]
break
elif a[0] < b[0] and a[1] > b[1]:
del ranges[i + 1]
break
elif a[0] > b[0] and a[1] < b[1]:
del ranges[i]
break
elif a[1] < b[0]:
pass
elif a[0] <= b[1] and a[1] >= b[0]:
ranges[i] = (a[0], b[1])
del ranges[i + 1]
break
else:
raise Exception("uhoh", a, b)
else:
return ranges
return ranges
def mdist(dx, dy):
return abs(dx) + abs(dy)
def xdist(dm, dy):
x = dm - abs(dy)
if x <= 0:
return 0
return x
def solve(lines: list[str], yt):
sensors = []
bacons = set()
for (i, line) in enumerate(lines):
digits = lib.str_to_ints(line)
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sx, sy, bx, by = digits
sm = mdist(bx - sx, by - sy)
sensors.append([sx, sy, sm])
bacons.add((bx, by))
ranges = []
for (sx, sy, sm) in sensors:
x_range = xdist(sm, yt - sy)
if x_range == 0:
continue
r = (sx - x_range, sx + x_range)
# print(f"{sx=} {sy=} {r=}")
ranges.append(r)
ranges = unify_ranges(ranges)
r = 0
for (a, b) in ranges:
r += b - a + 1
for (bx, by) in list(bacons):
if by == yt and bx >= a and bx <= b:
r -= 1
# 140:00 I don't know what a Manhattan distance is.
return r
def solve2(lines: list[str], xymax):
sensors = []
bacons = set()
for (i, line) in enumerate(lines):
digits = lib.str_to_ints(line)
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sx, sy, bx, by = digits
sm = mdist(bx - sx, by - sy)
sensors.append([sx, sy, sm])
bacons.add((bx, by))
finds = []
for yt in range(0, xymax):
ranges = []
for (sx, sy, sm) in sensors:
x_range = xdist(sm, yt - sy)
if x_range == 0:
continue
r = (sx - x_range, sx + x_range)
ranges.append(r)
ranges = unify_ranges(ranges)
if ranges[0][0] > 0:
raise Exception("Bacon at 0.")
elif ranges[-1][-1] < xymax:
raise Exception("Bacon at xymax.")
for i in range(len(ranges) - 1):
if ranges[i + 1][0] - ranges[i][1] > 1:
finds.append((ranges[i][1] + 1, yt))
if len(finds) != 1:
raise Exception("TOO MANY FINDS")
else:
x, y = finds[0]
return x * 4000000 + y
# 10:00
def main():
lines = lib.str_to_lines_no_empty(EXAMPLE)
print("Example 1:", solve(lines, 10))
lines = lib.str_to_lines_no_empty(open("i15.txt").read())
print("Solution 1:", solve(lines, 2000000))
lines = lib.str_to_lines_no_empty(EXAMPLE)
print("Example 2:", solve2(lines, 20))
lines = lib.str_to_lines_no_empty(open("i15.txt").read())
print("Solution 2:", solve2(lines, 4000000))
if __name__ == "__main__":
main()