Advent of Code 2020: Python Solution Day 14

#adventofcode #python #algorithms #challenge

Today's challenge was associated with binary system and it was pretty tricky too. I had to take help from here. I also have updated my repository here.

Please share your solution too.

Part 1

with open("day14.txt", 'r') as fp:
    lines = [line.rstrip() for line in fp.readlines()]

memory = {}
masks = []
curr_mask = None
curr_value = None
curr_address = None

for line in lines:
    k, v = line.split(" = ")
    if k == "mask":
        masks.append(v)
        curr_mask = v
    else:
        # get address
        curr_address = int(k[4:-1])
        curr_value = int(v)       

        bin_value = list(bin(curr_value)[2:].zfill(36))
        new_value = [0] * 36

        for i, (mask, value) in enumerate(zip(curr_mask, bin_value)):
            # do nothing if X
            if mask == "X":
                new_value[i] = value
            else:
                # change value to mask else
                new_value[i] = mask

        memory[curr_address] = int("".join(new_value), 2)
print(f"Part one solution: {sum(memory.values())}")

Part 2

"""
If the bitmask bit is 0, the corresponding memory address bit is unchanged.
If the bitmask bit is 1, the corresponding memory address bit is overwritten with 1.
If the bitmask bit is X, the corresponding memory address bit is floating.
"""
with open("day14.txt", 'r') as fp:
    lines = [line.rstrip() for line in fp.readlines()]

memory = {}
for line in lines:
    k, v = line.split(" = ")
    if k == "mask":
        masks.append(v)
        curr_mask = v
    else:
        # get address
        curr_address = int(k[4:-1])
        curr_value = int(v)       

        bin_add = list(bin(curr_address)[2:].zfill(36))
        new_add = ["0"] * 36

        v = len(list(bin(curr_address)[2:]))

        for i, (mask, value) in enumerate(zip(curr_mask, bin_add)):
            # if mask bit is floating then keep it floating on new address too
            if mask == "X":
                new_add[i] = "X"
            elif mask == "0":

                # change value to mask else
                new_add[i] = value
            elif mask == "1":
                new_add[i] = "1"

        new_add = "".join(new_add)

        # count floatings
        num_poss = new_add.count("X")

        flucts = []
        for i in range(2**num_poss):
            flucts.append( list(bin(i)[2:].zfill(num_poss)))

        for fluct in flucts:
            i = 0
            nadd = ""
            for a in new_add:
                if a == "X":
                    nadd+=str(fluct[i])
                    i+=1
                else:
                    nadd+=str(a)
            memory[int(nadd, 2)]=curr_value
sum(memory.values())

Top comments (4)

rozbrajaczpoziomow • Dec 14 '20

So I have smaller code for part 1. (I'd like to note, that instead of changing the file on-the-fly, i just assign the variable prompt as (in this case) an array of strings of every line)

import re
prompt = (input)
bitmask = -1
memory = []

def pad36(pad):
    return ('0' * (36 - len(pad))) + pad

for command in prompt:
    if(command.startswith('mask')):
        bitmask = re.findall(r'mask = (.*)', command)[0]
    elif(command.startswith('mem')):
        index = int(re.findall(r'mem\[(.*)\]', command)[0])
        value = int(re.findall(r' = (.*)', command)[0])
        valuebin = pad36(bin(value)[2:])
        finalbin = ''
        for iMask in range(0, len(bitmask)):
            if(bitmask[iMask] == 'X'):
                finalbin += valuebin[iMask]
            else:
                finalbin += bitmask[iMask]
        final = int(finalbin, 2)
        while(len(memory) <= index + 5):
            memory.append(0)
        memory[index] = final


print('[Solv]', sum(memory))