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Created Dec 3, 2020
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import itertools
from math import prod
with open('input.txt', 'r') as infile:
data = [line.strip('\n') for line in infile]
#Solution in one line:
print ("The answer to part 1 is: " + str(len([line for line in enumerate(data) if line[1][(line[0]*3) % len(line[1])] == '#'])))
#More verbose solution with the same method:
e = enumerate(data)
total = 0
lineLength = len(data[0])
for line in e:
charpos = (line[0]*3) % lineLength
if (line[1][charpos] == '#'): total += 1
print(f"The answer to part 1 is: {total}")
#Solution to part 2 in few lines using list comprehensions:
def getSlopeTrees(slope, over, down):
return len([line for line in enumerate(slope) if (line[0] % down == 0) and ((line[0]*over)/down).is_integer() and (line[1][int((line[0]*over)/down) % len(line[1])] == '#')])
testSteps = [(1,1),(3,1),(5,1),(7,1),(1,2)]
print (f"The answer to part 2 is : {prod([getSlopeTrees(data, *t) for t in testSteps])}")
#A functions that was useful in troubleshooting some list indexing issues:
def getSlopeTreesVerbose(slope, over, down):
total = 0
for line in enumerate(slope):
print(line, end = "\t")
readThisLine = (line[0] % down == 0)
print(f"Line[0] mod Down is 0: {readThisLine}", end = "\t")
treePosition = ((line[0]*over)/down) % len(line[1])
print(f"Looking at position: {treePosition}", end = "\t")
if treePosition.is_integer():
treePosition = int(treePosition)
lineHasTree = (line[1][treePosition] == '#')
print(f"Is tree? {lineHasTree}")
if readThisLine and lineHasTree: total = total + 1
return total
#Print the intermediate results of testing our various setups:
for t in testSteps:
print (f"For test Right {t[0]}, down {t[1]}, we hit {getSlopeTrees(data, *t)} trees")
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