Still non-working part 2. But I have an idea.

src/aoc2025/Day10.kt

@@ -1,8 +1,10 @@
 package aoc2025
 
+import calcCanonicalPrimesSieveOfEratosthenes
 import println
 import readInput
 import splitInts
+import java.math.BigInteger
 import java.util.*
 
 /*
@@ -29,7 +31,6 @@ fun main() {
             val toggles =
                 stuff.drop(1).dropLast(1)
                     .map { it.removeSurrounding("(", ")").splitInts(",").fold(0) { acc, v -> acc + (1 shl v) } }
-                    .sortedByDescending { it.countOneBits() }
                     .toIntArray()
             val joltages = stuff.last().removeSurrounding("{", "}").splitInts(",").toIntArray()
             machines.add(Machine(machSize, target, toggles, joltages))
@@ -93,6 +94,63 @@ fun main() {
     fun part2(input: List<String>): Int {
         val machines = parse(input)
 
+        val primes = calcCanonicalPrimesSieveOfEratosthenes(10000)
+        var sumButts = 0
+        for (m in machines) {
+            println()
+            val maxJoltage = m.joltage.max()
+            val numBits = 32 - maxJoltage.countLeadingZeroBits()
+            val bigTarget = m.joltage.foldIndexed(BigInteger.ZERO) { index, acc, i -> acc.plus(BigInteger.valueOf(i.toLong()).shiftLeft(numBits * index)) }
+            val bigToggles = ArrayList<Pair<BigInteger, BigInteger>>()
+            for (t in m.toggles) {
+                var tt = t
+                var bigToggle = BigInteger.ZERO
+                var shift = 0
+                while (tt > 0) {
+                    if (tt and 1 != 0) {
+                        bigToggle = bigToggle.plus(BigInteger.ONE.shiftLeft(shift))
+                    }
+                    shift += numBits
+                    tt = tt shr 1
+                }
+                val maxValue = bigTarget.divide(bigToggle).and(BigInteger.ONE.shiftLeft(numBits).minus(BigInteger.ONE)).toInt() + 1
+                println(maxValue)
+                if (maxValue > 0) {
+                    bigToggles.add(bigToggle to BigInteger.valueOf(maxValue.toLong()))
+                }
+            }
+            var presses = BigInteger.ONE
+            var leastFingers = Integer.MAX_VALUE
+            val maxPresses = bigToggles.fold(BigInteger.ONE) { acc, bt -> acc.multiply(bt.second) }
+            while (presses <= maxPresses) {
+                var pe = 0
+                var pr = presses
+                var bt = bigTarget
+                var fingers = 0
+                while (pe < bigToggles.size && pr > BigInteger.ZERO) {
+                    val f = pr.mod(bigToggles[pe].second)
+                    fingers += f.toInt()
+                    if (fingers > leastFingers) break
+                    bt = bt.minus(bigToggles[pe].first.multiply(f))
+                    if (bt <= BigInteger.ZERO) break
+                    pr = pr.divide(bigToggles[pe].second)
+                    pe++
+                }
+                if (bt == BigInteger.ZERO) {
+                    leastFingers = leastFingers.coerceAtMost(fingers)
+                    break
+                }
+                presses = presses.plus(BigInteger.ONE)
+            }
+            println(leastFingers)
+            sumButts += leastFingers
+        }
+        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
@@ -129,12 +187,7 @@ fun main() {
 
             // press all buttons regarding their minimal count (if any)
             for (t in toggles) {
-                if (pressCount[t.idx] + t.min > t.max || !applyJoltage(
+                if (pressCount[t.idx] + t.min > t.max || !applyJoltage(jolts, t, times = t.min)) throw IllegalStateException()
-                        jolts,
-                        t,
-                        times = t.min
-                    )
-                ) throw IllegalStateException()
                 pressCount[t.idx] += t.min
             }
             // this is the starting point for the exhaustive search
@@ -151,7 +204,7 @@ fun main() {
                 }
                 for (t in toggles) {
                     if (tc[t.idx] + 2 <= t.max) {
-                        val maxTimes = findMaxButtonPresses(j, t)
+                        val maxTimes = 1//findMaxButtonPresses(j, t)
                         if (maxTimes > 0) {
                             val nj = j.copyOf()
                             if (applyJoltage(nj, t, maxTimes)) {
@@ -178,7 +231,7 @@ fun main() {
     val testInputPart2Result = part2(testInput)
     println("Part 2 Test: $testInputPart2Result")
     check(testInputPart1Result == 7)
-    //check(testInputPart2Result == 33)
+    check(testInputPart2Result == 33)
 
     val input = readInput("aoc2025/Day10")
     part1(input).println()