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Intermediate commit before I break stuff.

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This commit is contained in:
Chris Hodges 2025-12-11 15:30:13 +01:00
parent 2190f9e1ac
commit de3b0795e3
2 changed files with 63 additions and 119 deletions
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54
src/PrimesAndFactors.kt
View File

@ -187,7 +187,59 @@ fun gcdPositive(aIn: Long, bIn: Long): Long {
return a shl shift
}
fun calcPrimeFactorsAndPhi(n: Long, primes: MutableList<Long>, allPrimes: MutableSet<Long>): Pair<List<Pair<Long, Int>>, Long> {
// ax + by = gcdExtendedPositive(a, b)
fun extendedGcd(a: Long, b: Long): Pair<Long, Pair<Long, Long>> {
var old_r = a
var r = b
var old_s = 1L
var s = 0L
var old_t = 0L
var t = 1L
while (r != 0L) {
val q = old_r / r
val rtmp = old_r
old_r = r
r = rtmp - q * r
val stmp = old_s
old_s = s
s = stmp - q * s
val ttmp = old_t
old_t = t
t = ttmp - q * t
}
return old_r to (old_s to old_t)
}
fun extendedGcd(v: List<Long>): Pair<Long, List<Long>> {
if (v.size < 2) throw IllegalArgumentException("Expected at least 2 elements")
val gcds = ArrayList<Long>(v.size)
val coeffs = ArrayList<Long>(v.size)
var (gcd, p1) = extendedGcd(v[0], v[1])
coeffs.add(p1.first)
coeffs.add(p1.second)
gcds.add(gcd)
gcds.add(gcd)
for (i in 2 until v.size) {
val (gcdnew, pi) = extendedGcd(gcd, v[i])
gcd = gcdnew
coeffs.add(pi.second)
gcds.add(gcd)
}
for (i in gcds.indices) {
if (gcds[i] != gcd) {
coeffs[i] *= gcds[i] / gcd
}
}
return gcd to coeffs
}
fun calcPrimeFactorsAndPhi(
n: Long,
primes: MutableList<Long>,
allPrimes: MutableSet<Long>
): Pair<List<Pair<Long, Int>>, Long> {
val factors = ArrayList<Pair<Long, Int>>()
var phi = 1L
var rem = n

128
src/aoc2025/Day10.kt
View File

@ -1,14 +1,13 @@
package aoc2025
import chineseRemainder
import gcdPositive
import extendedGcd
import primeFactors
import primeSequence
import println
import readInput
import sieveOfErastosthenes
import splitInts
import java.util.*
/*
--- Day 10: Factory ---
@ -60,40 +59,6 @@ fun main() {
return sumButts
}
data class Toggle(val idx: Int, val v: Int, var min: Int = 0, var max: Int = Int.MAX_VALUE)
fun applyJoltage(jolts: IntArray, toggle: Toggle, times: Int = 1): Boolean {
var tt = toggle.v
var jp = 0
var valid = true
while (tt != 0) {
if (tt and 1 != 0) {
jolts[jp] -= times
if (jolts[jp] < 0) {
valid = false
break
}
}
tt = tt shr 1
jp++
}
return valid
}
fun findMaxButtonPresses(jolts: IntArray, toggle: Toggle): Int {
var tt = toggle.v
var jp = 0
val maxPresses = Int.MAX_VALUE
while (tt != 0) {
if (tt and 1 != 0) {
maxPresses.coerceAtMost(jolts[jp] / 2)
}
tt = tt shr 1
jp++
}
return maxPresses
}
fun part2(input: List<String>): Int {
val machines = parse(input)
@ -105,7 +70,12 @@ fun main() {
val maxJoltage = m.joltage.max()
val primefactors = primes.dropWhile { it <= maxJoltage }.take(m.size).map { it.toLong() }
if (primefactors.size != m.size) throw IllegalStateException()
val bigTarget = m.joltage.foldIndexed(0L) { index, acc, i -> acc.plus(i.toLong() * primefactors[index]) }
val primePow = LongArray(m.size)
primePow[0] = primefactors[0]
for (i in 1 until m.size) {
primePow[i] = primePow[i - 1] * primefactors[i]
}
val bigTarget = m.joltage.foldIndexed(0L) { index, acc, i -> acc.plus(i.toLong() * primePow[index]) }
val bigToggles = ArrayList<Long>()
for (t in m.toggles) {
var tt = t
@ -113,9 +83,9 @@ fun main() {
var idx = 0
while (tt > 0) {
if (tt and 1 != 0) {
bigToggle += primefactors[idx]
bigToggle += primePow[idx]
}
idx += 1
idx++
tt = tt shr 1
}
bigToggles.add(bigToggle)
@ -124,10 +94,7 @@ fun main() {
// j0 * bigtoggle[0] + j1 * bigtoggle[1] + ... = bigTarget
// is a Linear Diophantine equation that can be solved with the extended Euclidean algorithm
var gcd = gcdPositive(bigToggles[0], bigToggles[1])
for (i in 2 until bigToggles.size) {
gcd = gcdPositive(gcd, bigToggles[i])
}
val (gcd, coeffients) = extendedGcd(bigToggles)
if (bigTarget % gcd != 0L) throw IllegalStateException()
val factorMap = HashMap<Long, Long>()
@ -152,81 +119,6 @@ fun main() {
return sumButts
}
fun part2old(input: List<String>): Int {
val machines = parse(input)
var sumButts = 0
for (m in machines) {
// generate toggles and calculate the global maximum of toggle presses for this toggle
val toggles = m.toggles.mapIndexed { i, t ->
Toggle(
i,
t,
max = IntRange(0, m.size).filter { b -> t and (1 shl b) != 0 }.minOf { m.joltage[it] })
}
// try to calculate a minimum number of toggle presses as the joltage needs to be reached exactly
val subsets = Array(m.size) { toggles.filter { v -> (1 shl it) and v.v != 0 }.toTypedArray() }
for (v in toggles) {
var minT = 0
for (b in 0 until m.size) {
var rj = m.joltage[b]
var found = false
for (s in subsets[b]) {
if (s === v) {
found = true
} else {
rj -= s.max
if (rj < 0) break
}
}
if (found) minT = minT.coerceAtLeast(rj)
}
if (minT > v.max) throw IllegalStateException()
v.min = minT
}
var minPushes = Int.MAX_VALUE
val jolts = m.joltage.copyOf()
val pressCount = IntArray(m.toggles.size)
// press all buttons regarding their minimal count (if any)
for (t in toggles) {
if (pressCount[t.idx] + t.min > t.max || !applyJoltage(jolts, t, times = t.min)) throw IllegalStateException()
pressCount[t.idx] += t.min
}
// this is the starting point for the exhaustive search
val pq = PriorityQueue(compareBy<Pair<IntArray, IntArray>> { it.second.sum() })
pq.add(jolts to pressCount)
while (pq.isNotEmpty()) {
val (j, tc) = pq.poll()
val pushes = tc.sum()
if (pushes >= minPushes) break
// if the joltage has counted down to zero, we're done
if (j.sum() == 0) {
minPushes = pushes
break
}
for (t in toggles) {
if (tc[t.idx] + 2 <= t.max) {
val maxTimes = 1//findMaxButtonPresses(j, t)
if (maxTimes > 0) {
val nj = j.copyOf()
if (applyJoltage(nj, t, maxTimes)) {
val ntc = tc.copyOf()
ntc[t.idx] += maxTimes
pq.add(nj to ntc)
}
}
}
}
}
println("$minPushes")
sumButts += minPushes
}
return sumButts
}
// test if implementation meets criteria from the description, like:
val testInput = inlineTestInput.trim().reader().readLines()
//val testInput = readInput("aoc2025/Day10_test")