advent-of-code/2021
advent-of-code/2021
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day(03): refactor

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Signed-off-by: Matej Focko <mfocko@redhat.com>
This commit is contained in:
Matej Focko 2021-12-04 15:57:28 +01:00
parent 91aa2e41b7
commit 47f865d9aa
1 changed files with 41 additions and 49 deletions
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90
src/day03/Day03.kt
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@ -2,56 +2,48 @@ package day03
import readInput
fun toBits(input: List<String>): List<List<Int>> = input.map { row ->
row.map { if (it == '1') 1 else 0 }
}
fun part1(input: List<List<Int>>): Int {
var gamma = 0
var epsilon = 0
for (i in input[0].indices) {
gamma = gamma.shl(1)
epsilon = epsilon.shl(1)
val ones = input.indices.sumOf { input[it][i] }
if (2 * ones > input.size) gamma++ else epsilon++
}
return epsilon * gamma
}
fun part2(input: List<List<Int>>): Int {
fun part2Helper(predicate: (Int, Int) -> Boolean): Int {
var wanted = input.indices.toList()
var i = 0
while (wanted.size > 1) {
val ones = wanted.sumOf { input[it][i] }
val wantedBit = if (predicate(ones, wanted.size)) 1 else 0
wanted = wanted.filter { input[it][i] == wantedBit }.toList()
i++
}
return input[wanted[0]].fold(0) { n, d -> 2 * n + d }
}
val oxygenGeneratorRating = part2Helper { ones, length -> 2 * ones >= length }
val co2ScrubberRating = part2Helper { ones, length -> 2 * ones < length }
return oxygenGeneratorRating * co2ScrubberRating
}
fun main() {
fun toBits(input: List<String>): List<List<Int>> {
return input.map { row ->
row.map { if (it == '1') 1 else 0 }
}
}
fun part1(input: List<List<Int>>): Int {
var gamma = 0
var epsilon = 0
for (i in input[0].indices) {
gamma = gamma.shl(1)
epsilon = epsilon.shl(1)
val ones = input.indices.map { input[it][i] }.sum()
if (2 * ones > input.size) {
gamma++
} else {
epsilon++
}
}
return epsilon * gamma
}
fun part2(input: List<List<Int>>): Int {
fun part2Helper(predicate: (Int, Int) -> Boolean): Int {
var wanted = input.indices.toList()
var i = 0
while (wanted.size > 1) {
val ones = wanted.sumOf { input[it][i] }
val wantedBit = if (predicate(ones, wanted.size)) 1 else 0
wanted = wanted.filter { input[it][i] == wantedBit }.toList()
i++
}
return input[wanted[0]].fold(0) { n, d -> 2 * n + d }
}
val oxygenGeneratorRating = part2Helper { ones, length -> 2 * ones >= length }
val co2ScrubberRating = part2Helper { ones, length -> 2 * ones < length }
return oxygenGeneratorRating * co2ScrubberRating
}
val testInput = toBits(readInput(3, "test_input"))
val input = toBits(readInput(3, "input"))