My Advent of Code solutions in Python.
kevinyap.ca/2019/12/going-fast-in-advent-of-code/
advent-of-code
python
Add solution for 2023/16
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+64
2023/day16.py
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2023/day16.py
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import fileinput
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from utils import Point, DIRS, N, E, S, W
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# Parse problem input.
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GRID = {}
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for y, line in enumerate(fileinput.input()):
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for x, c in enumerate(line.strip()):
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GRID[Point(x, y)] = c
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MAX_X = x
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MAX_Y = y
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def simulate_light(grid, start, initial_d):
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photons = [(start, initial_d)]
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seen = set()
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while photons:
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photon, d = photons.pop()
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if photon not in grid:
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continue
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if (photon, d) in seen:
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continue
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seen.add((photon, d))
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if grid[photon] == '.':
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photons.append((photon + d, d))
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elif grid[photon] == '/':
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nd = [W, E, S, N][[N, S, E, W].index(d)]
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photons.append((photon + nd, nd))
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elif grid[photon] == '\\':
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nd = [E, W, N, S][[N, S, E, W].index(d)]
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photons.append((photon + nd, nd))
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elif grid[photon] == '|':
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if d in (N, S):
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photons.append((photon + d, d))
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else:
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photons.append((photon + N, N))
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photons.append((photon + S, S))
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elif grid[photon] == '-':
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if d in (E, W):
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photons.append((photon + d, d))
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else:
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photons.append((photon + E, E))
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photons.append((photon + W, W))
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return len(set(p for p, d in seen))
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def part_2_starts(grid):
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for x in range(MAX_X):
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yield Point(x, 0), N
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yield Point(x, MAX_Y - 1), S
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for y in range(MAX_Y):
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yield Point(0, y), E
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yield Point(MAX_X - 1, y), W
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print("Part 1:", simulate_light(GRID, Point(0, 0), E))
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print("Part 2:", max(simulate_light(GRID, p, d) for p, d in part_2_starts(GRID)))