aoc/2020/14/14.py

84 lines
2.3 KiB
Python
Raw Normal View History

2020-12-14 06:47:41 +00:00
def read_file():
with open("input.txt","r") as f:
return f.read().split('\n')
def process(instructions):
mask = "X"*36
memory = {}
for instruction in instructions:
if instruction[0:4] == "mask":
mask = instruction[7:] # trim "mask = "
else:
address = instruction[4:].split(']')[0] # trim "mem[", then split off everyting after "]"
value = instruction.split('=')[1][1:] # split, take the second half, and trim the space
value = str(format(int(value),'036b')) # 36 bits of binary, with leading 0s
result = ""
for m, b in zip(mask, value):
if m == "0" or m == "1": # mask is applied
result += m # so rewrite with mask bit
else: # m == "X"
result += b # so keep value bit
memory[address] = result
return memory
def part1(instructions):
memory = process(instructions)
result = 0
for address in memory:
result += int(memory[address],2)
return result
def addresses(address, mask):
addresses = []
# TODO: learn how to use itertools to avoid having to manually do this stuff? bc "there must be a better way" ~raymond hettinger
temp = ""
for i in range(len(mask)):
if mask[i] == "0":
temp += address[i]
elif mask[i] == "1":
temp += mask[i]
else: # mask[i] == "X"
temp += "X"
addresses.append(temp)
iterations = mask.count("X")
for i in range(iterations): # replace each X one by one
a0s = []
a1s = []
for a in addresses:
a0 = a.replace("X","0",1) # replace first X with 0
a1 = a.replace("X","1",1) # replace first X with 1
a0s.append(a0)
a1s.append(a1)
addresses = a0s + a1s # repopulate list -- should double in size
return addresses
def process2(instructions):
mask = "0"*36
memory = {}
for instruction in instructions:
if instruction[0:4] == "mask":
mask = instruction[7:]
else:
address = instruction[4:].split(']')[0]
address = str(format(int(address),'036b'))
value = instruction.split('=')[1][1:]
value = str(format(int(value),'036b'))
exploded_addrs = addresses(address, mask) # explode mask due to quantum bits
for address in exploded_addrs:
memory[address] = value
return memory
def part2(instructions):
memory = process2(instructions)
result = 0
for address in memory:
result += int(memory[address],2)
return result
def main():
instructions = read_file()
print(part1(instructions), part2(instructions))
if __name__ == "__main__":
main()