37 lines
1.3 KiB
Kotlin
37 lines
1.3 KiB
Kotlin
package be.vandewalleh.aoc.days
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import be.vandewalleh.aoc.utils.BaseDay
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import be.vandewalleh.aoc.utils.input.Day
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@Day
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class Day03 : BaseDay() {
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override fun part1(): Int {
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val moreOnes = input.lines.value[0].indices
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.map { i -> input.lines.value.map { it[i] } }
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.map { it.count { it == '1' } >= it.size / 2 }
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val gamma = moreOnes.joinToString("") { if (it) "1" else "0" }.toInt(radix = 2)
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val epsilon = moreOnes.joinToString("") { if (!it) "1" else "0" }.toInt(radix = 2)
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return gamma * epsilon
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}
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override fun part2(): Any {
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val o2 = findNumber(input.lines.value) { ones, zeros -> if (ones >= zeros) '1' else '0' }
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val co2 = findNumber(input.lines.value) { ones, zeros -> if (zeros <= ones) '0' else '1' }
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return o2 * co2
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}
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private fun findNumber(input: List<String>, keep: (Int, Int) -> Char): Int {
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var numbers = input
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for (i in this.input.lines.value[0].indices) {
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if (numbers.size == 1) break
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val eachCount = numbers.map { it[i] }.groupingBy { it }.eachCount()
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val ones = eachCount['1'] ?: 0
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val zeros = eachCount['0'] ?: 0
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val maj = keep(ones, zeros)
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numbers = numbers.filter { it[i] == maj }
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}
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return numbers[0].toInt(2)
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}
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}
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