Idiomatic Kotlin: Solving Advent of Code Puzzles, Passport Validation

Today in “Idiomatic Kotlin”, we’re looking at day 4 of the Advent of Code 2020 challenges, in which we tackle a problem that feels as old as programming itself: input sanitization and validation. Day 4. Passport processing We need to build a passport scanner that, given a batch of input text, can count how many passports are valid. You can find the complete task description at Like many challenges, we first inspect our input: