Day2.kt

package day02

import util.readFile

class Day2(private val inputFile: String) {

    private val lines: List<String> = readFile(inputFile)
    private val lineRegex = """(\d+)-(\d+) ([a-z]):\s([a-z]+)""".toRegex()

    fun part1(): Int = countValidPasswords(::validatorPart1)
    fun part2(): Int = countValidPasswords(::validatorPart2)
    fun countValidPasswords(validator: (Int, Int, String, String) -> Boolean): Int = lines.count { checkPassword(it, validator) }
    fun validatorPart1(minOccurs: Int, maxOccurs: Int, letter: String, password: String): Boolean = """^([^${letter}]*$letter[^$letter]*){$minOccurs,$maxOccurs}${'$'}""".toRegex().matches(password)
    fun validatorPart2(pos1: Int, pos2: Int, letter: String, password: String): Boolean = password[pos1 - 1].toString().equals(letter).xor(password[pos2 - 1].toString().equals(letter))
    fun checkPassword(passwordLine: String, validator: (Int, Int, String, String) -> Boolean): Boolean {
        val (num1, num2, letter, password) = lineRegex.find(passwordLine)!!.destructured
        return validator(num1.toInt(), num2.toInt(), letter, password)
    }
}