package be.vandewalleh.aoc.days

import be.vandewalleh.aoc.utils.BaseDay
import be.vandewalleh.aoc.utils.input.Day

@Day
class Day03 : BaseDay() {
    override fun part1(): Int {
        val moreOnes = input.lines.value[0].indices
            .map { i -> input.lines.value.map { it[i] } }
            .map { it.count { it == '1' } >= it.size / 2 }

        val gamma = moreOnes.joinToString("") { if (it) "1" else "0" }.toInt(radix = 2)
        val epsilon = moreOnes.joinToString("") { if (!it) "1" else "0" }.toInt(radix = 2)
        return gamma * epsilon
    }

    override fun part2(): Any {
        val o2 = findNumber(input.lines.value) { ones, zeros -> if (ones >= zeros) '1' else '0' }
        val co2 = findNumber(input.lines.value) { ones, zeros -> if (zeros <= ones) '0' else '1' }
        return o2 * co2
    }

    private fun findNumber(input: List<String>, keep: (Int, Int) -> Char): Int {
        var numbers = input
        for (i in this.input.lines.value[0].indices) {
            if (numbers.size == 1) break
            val eachCount = numbers.map { it[i] }.groupingBy { it }.eachCount()
            val ones = eachCount['1'] ?: 0
            val zeros = eachCount['0'] ?: 0
            val maj = keep(ones, zeros)
            numbers = numbers.filter { it[i] == maj }
        }
        return numbers[0].toInt(2)
    }
}