Advent of Code 2016 - Day 6 - Signals and Noise

On the sixth day of Advent of Code 2016 we are required to work what the error-corrected message is attempted to be sent to Santa.

Part 1

Based on the message signal provided (our input), we can work out the error-corrected message being sent by finding the most frequent character for each position. In a one-liner we are able to decode the correct message and return this as our desired answer 🌟.

def part1(input):
    return ''.join(Counter(col).most_common()[0][0]
                   for col in zip(*input.splitlines()))

This solution highlights how powerful Python’s list comprehension and standard library is, transposing the message characters and using the Counter collection again to tally up their frequencies.

Part 2

For part two, we are instead required to use a modified repetition code, taking the least common occurrence per character position. Thanks to the Counter collection again, we can trivially modify the occurrence being plucked out (now the least common) and return in a similar fashion 🌟.

def part2(input):
    return ''.join(Counter(col).most_common()[-1][0]
                   for col in zip(*input.splitlines()))

I really do not feel you could be more expressive and consise in a solution than how we have been able to model today’s problem in Python.