46 lines
1.3 KiB
Python
46 lines
1.3 KiB
Python
def parse_input(input: list[str]):
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l = [(x, y) for (y, line) in enumerate(input) for (x, c) in enumerate(line) if c == '#']
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start = [(x, y) for (y, line) in enumerate(input) for (x, c) in enumerate(line) if c == 'S'][0]
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goal = [(x, y) for (y, line) in enumerate(input) for (x, c) in enumerate(line) if c == 'E'][0]
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w = max([x for (x, y) in l])
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h = max([y for (x, y) in l])
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return l, w, h, start, goal
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def sp(points, w, h, start, goal):
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visited = dict()
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(sx, sy) = start
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stack = [(sx, sy, 0)]
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while len(stack) > 0:
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(x, y, c) = stack.pop(0)
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if (x, y) == goal:
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return c
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if (x, y) in visited:
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continue
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visited[(x, y)] = c
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for (a, b) in [(x+nx, y+ny) for (nx, ny) in [(0, 1), (1, 0), (0, -1), (-1, 0)]]:
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if 0 <= a <= w and 0 <= b <= w and (a, b) not in points:
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stack.append((a, b, c + 1))
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return None
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source = "input/day20.txt"
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with open(source, 'r') as f:
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data = f.read()
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(points, w, h, start, goal) = parse_input(data.strip().split('\n'))
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bottomline = sp(set(points), w, h, start, goal)
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print(bottomline)
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atleast100 = 0
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for p in points:
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remains = [x for x in points if p != x]
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pathlength = sp(set(remains), w, h, start, goal)
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if bottomline - pathlength >= 100:
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atleast100 += 1
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print("task 1: " + str(atleast100))
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