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Optimize part1

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This commit is contained in:
Hubert Van De Walle 2020-12-09 10:32:21 +01:00
parent 3399bd8c43
commit 9aa3c1cace
1 changed files with 18 additions and 15 deletions
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33
days/src/main/kotlin/Day09.kt
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@ -10,23 +10,26 @@ class Day09(@Lines val input: Input<LongArray>) {
private var part1Result = 0L private var part1Result = 0L
fun part1() = input.value fun part1(): Long? {
.toList() val longs = input.value
.asSequence()
.windowed(size = 26)
.find { !isValid(it) }
?.last()
?.also { part1Result = it }
private fun isValid(items: List<Long>): Boolean { for (windowStart in 0 until longs.size - 26) {
val preamble = items.take(25) val last = longs[windowStart + 25]
val last = items.last() if (!isValid(windowStart, last)) {
part1Result = last
return last
}
}
for (e in preamble) { return null
for (f in preamble) { }
if (e + f == last && e != f) {
return true private fun isValid(windowStart: Int, last: Long): Boolean {
} for (i in windowStart..windowStart + 25) {
for (j in windowStart + 1..windowStart + 25) {
val f = input.value[i]
val s = input.value[j]
if (f + s == last && f != s) return true
} }
} }
return false return false