advent-of-code/src/Utils.kt

import java.io.File
import java.math.BigInteger
import java.security.MessageDigest

/**
 * Reads lines from the given input txt file.
 */
fun readInput(name: String) = File("src", "$name.txt")
    .readLines()

fun listOfIntegerLists(input: List<String>): ArrayList<List<Int>> {
    val output = ArrayList<List<Int>>()
    var currList = ArrayList<Int>()
    for(i in input)
    {
        if(i.isEmpty()){
            output.add(currList)
            currList = ArrayList<Int>()
        } else {
            currList.add(i.toInt())
        }
    }
    if(currList.isNotEmpty())
    {
        output.add(currList)
    }
    return output
}

/**
 * Converts string to md5 hash.
 */
fun String.md5() = BigInteger(1, MessageDigest.getInstance("MD5").digest(toByteArray()))
    .toString(16)
    .padStart(32, '0')

/**
 * The cleaner shorthand for printing output.
 */
fun Any?.println() = println(this)