67 lines
1.8 KiB
Python
67 lines
1.8 KiB
Python
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import itertools
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import math
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def tree_line(init):
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return {
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"init-len": len(init),
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"known": '',
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"rest": itertools.repeat(init)
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}
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def tree_line_at(pos, tree_line):
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needed = (pos + 1) - len(tree_line["known"])
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# internally advance the tree line to the position requested
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if needed > 0:
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tree_line["known"] = tree_line["known"] \
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+ ''.join(
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itertools.islice(
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tree_line["rest"],
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1+math.floor(needed / tree_line["init-len"])))
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# print(tree_line)
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return tree_line["known"][pos] == '#'
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def tree_at(linepos, pos, trees):
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return tree_line_at(pos, trees[linepos])
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def slope_positions(trees, right, down):
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line = 0
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pos = 0
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while line < len(trees):
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yield (line, pos)
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line = line + down
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pos = pos + right
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trees = []
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with open("./input", 'r') as f:
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for line in f:
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line = line.rstrip()
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trees.append(tree_line(line))
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# print(list(itertools.islice(trees[0], 5)))
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# print(list(map(
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# lambda x: tree_at(0, x, trees),
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# range(100)
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# )))
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# print(list(slope_positions(trees, right=3, down=1)))
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def count_slope_positions(trees, slope):
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count = 0
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for (line, pos) in slope:
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if tree_at(line, pos, trees):
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count = count + 1
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return count
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print(
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count_slope_positions(trees, slope_positions(trees, right=1, down=1))
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*
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count_slope_positions(trees, slope_positions(trees, right=3, down=1))
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*
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count_slope_positions(trees, slope_positions(trees, right=5, down=1))
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*
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count_slope_positions(trees, slope_positions(trees, right=7, down=1))
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*
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count_slope_positions(trees, slope_positions(trees, right=1, down=2))
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)
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# I realized I could have just used a modulo instead …
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