Day 4 Advent of Code 2016

from collections import Counter
import re

with open("day_4.txt") as f:
    inp_4 = f.read().strip()
inp_4 = inp_4.split('\n')

# Part 1

def is_real(s, k):
    s = Counter(s.replace('-', ''))
    counts = sorted(s.items(), key=lambda x: (-x[1], x[0]))
    return ''.join(map(lambda x: x[0], counts[:5])) == re.findall(r'\[(.*)\]', k)[0]

total = 0
inp_filter = []
for ele in inp_4:
    s, k = ele.rsplit('-', 1)
    if is_real(s, k):
        num = int(re.findall(r'\d+', k)[0])
        inp_filter.append([s, num])
        total += num

print(total)

# Part 2 (builds on part 1)

import string
def shift(s, k):
    s = s.split('-')
    k = k%26
    d = {}
    for c in string.ascii_lowercase:
        d[c] = (ord(c) - ord('a') + k)%26 + ord('a')
    table = str.maketrans(d)
    return ' '.join(i.translate(table) for i in s)

for s, k in inp_filter:
    b = shift(s, k)
    if "northpole" in b:
        print(k)
        break