Solution for part 2 of https://adventofcode.com/2021/day/10

submarine.kt

import java.util.*

private fun readChar(): Char = readString()[0]
private fun readChars(): CharArray = readString().toCharArray()
private fun readInt(): Int = readLine()!!.toInt()
private fun readInts(): List<Int> = readLine()!!.trim().split(" ").map(String::toInt)
private fun readLong(): Long = readLine()!!.toLong()
private fun readLongs(): List<Long> = readLine()!!.trim().split(" ").map(String::toLong)
private fun readString(): String = readLine()!!.trim()
private fun readStrings(): List<String> = readLine()!!.trim().split(" ")

fun main() {
	val opening = setOf('(', '[', '{', '<')
	val matching = mapOf(Pair('(', ')'), Pair('[', ']'), Pair('{', '}'), Pair('<', '>'))
	val score = mapOf(Pair('(', 1L), Pair('[', 2), Pair('{', 3), Pair('<', 4))
	var nextLine = readString()

	val scores = mutableListOf<Long>()

	nextLine@while (nextLine.isNotEmpty()) {
		var totalScore = 0L
		val stack = ArrayDeque<Char>()

		for (c in nextLine) {
			if (c in opening) stack.offerLast(c)
			else if (stack.isNotEmpty() && matching[stack.peekLast()] == c) stack.pollLast()
			else {
				nextLine = readString()
				continue@nextLine
			}
		}

		while (stack.isNotEmpty()) {
			totalScore *= 5
			totalScore += score[stack.pollLast()]!!
		}

		scores.add(totalScore)
		nextLine = readString()
	}

	scores.sort()

	println(scores[scores.size / 2])
}

/*

[({(<(())[]>[[{[]{<()<>>
[(()[<>])]({[<{<<[]>>(
(((({<>}<{<{<>}{[]{[]{}
{<[[]]>}<{[{[{[]{()[[[]
<{([{{}}[<[[[<>{}]]]>[]]


[({(<(())[]>[[{[]{<()<>>
[(()[<>])]({[<{<<[]>>(
{([(<{}[<>[]}>{[]{[(<()>
(((({<>}<{<{<>}{[]{[]{}
[[<[([]))<([[{}[[()]]]
[{[{({}]{}}([{[{{{}}([]
{<[[]]>}<{[{[{[]{()[[[]
[<(<(<(<{}))><([]([]()
<{([([[(<>()){}]>(<<{{
<{([{{}}[<[[[<>{}]]]>[]]

 */