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Revisited Day 22 for faster algorithm

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This commit is contained in:
Chris Hodges 2024-12-23 16:26:07 +01:00
parent 277bc6cc8e
commit 0d5809398c
1 changed files with 22 additions and 1 deletions
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23
src/aoc2024/Day22.kt
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@ -36,7 +36,7 @@ fun main() {
fun part1(input: List<String>) =
input.map(String::toInt).sumOf { priceSequence(it).elementAt(2000).toLong() }
fun part2(input: List<String>): Int {
fun part2bruteforce(input: List<String>): Int {
val strings = input.map(String::toInt).map {
val normalString = StringBuffer(2024)
val deltaString = StringBuffer(2024)
@ -70,6 +70,27 @@ fun main() {
}
}
fun part2(input: List<String>): Int {
val map = HashMap<Int, MutableList<Int>>()
input.map(String::toInt).forEach {
var lastd = 0
var code = 0
var countDown = 4
val seenArray = BooleanArray(19 * 19 * 19 * 19)
for (v in priceSequence(it).take(2001)) {
val d = v % 10
val delta = d - lastd
code = ((code * 19) % (19 * 19 * 19 * 19)) + (delta + 9)
if (--countDown < 0 && !seenArray[code]) {
map.getOrPut(code) { ArrayList() }.add(d)
seenArray[code] = true
}
lastd = d
}
}
return map.maxOf { it.value.sum() }
}
// test if implementation meets criteria from the description, like:
val testInput = inlineTestInput.trim().reader().readLines()
val testInput2 = inlineTestInput2.trim().reader().readLines()