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