66 lines
1.8 KiB
Python
66 lines
1.8 KiB
Python
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 …
|