Day 14, that wasn't easy to get correct

src/main/kotlin/com/basdado/adventofcode/day14/Day14.kt

@@ -0,0 +1,142 @@
+package com.basdado.adventofcode.day14
+
+import com.basdado.adventofcode.day14.Day14.Recipe.Companion.parse
+import com.basdado.adventofcode.lines
+import java.util.stream.Collectors
+import kotlin.math.ceil
+import kotlin.math.min
+
+const val DAY14_INPUT_PATH = "/day/14/input.txt"
+
+fun main() {
+    Day14.puzzle1()
+    Day14.puzzle2()
+}
+
+object Day14 {
+
+    fun puzzle1() {
+        val recipes = lines(DAY14_INPUT_PATH)
+            .map { parse(it) }
+            .collect(Collectors.toMap<Recipe, String, Recipe>({ it.output.first }, {it}))
+
+        println(calculateOreRequired(recipes))
+    }
+
+    fun puzzle2() {
+
+        val recipes = lines(DAY14_INPUT_PATH)
+            .map { parse(it) }
+            .collect(Collectors.toMap<Recipe, String, Recipe>({ it.output.first }, {it}))
+
+        var oreRequired = 0L
+        var stepSize = 1
+        val maxOre = 1_000_000_000_000L
+
+        var min = 1L
+        var max = 1_000_000_000_000L
+
+        while(min != max - 1) {
+
+            val guess = min + ((max - min) / 2)
+            if (calculateOreRequired(recipes, guess) > maxOre) {
+                max = guess
+            } else {
+                min = guess
+            }
+//            println("Result between $min and $max")
+
+        }
+        println(min)
+    }
+
+    private fun calculateOreRequired(recipes: MutableMap<String, Recipe>, fuelAmount: Long = 1L): Long {
+
+        var res = recipes["FUEL"]!!
+        if (fuelAmount > 1) {
+            res = Recipe(res.input.mapValues { it.value * fuelAmount }, Pair(res.output.first, res.output.second * fuelAmount))
+//            println("Required root recipe: $res")
+        }
+        // keep track of the remaining resources per type due to other reactions
+        val remaining = mutableMapOf<String, Long>()
+        val ingredientsRequiredCache = mutableMapOf<String, Set<String>>(Pair("ORE", emptySet()))
+        // Tactic: we keep simplifying the recipe until we are left with a recipe from ORE to FUEL
+        while (res.input.any { it.key != "ORE" }) {
+
+//            println(res)
+//            println("remaining: $remaining")
+
+            // We replace the ingredient that is not required by any other ingredients in the current recipe
+            val ingredientToReplace = res.input.keys.first {
+                res.input.keys.filter { o -> o != it }
+                    .none { o -> calculateIngredientsRequired(o, recipes, ingredientsRequiredCache).contains(it) }
+            }
+
+//            println("Replacing $ingredientToReplace")
+
+            val inputRequiredAmount =
+                res.input[ingredientToReplace] ?: error("Wait? The input $ingredientToReplace can't be found?")
+            val replacementRecipe = recipes[ingredientToReplace]!!
+            val replacementRecipeTimes =
+                ceil(inputRequiredAmount.toDouble() / replacementRecipe.output.second.toDouble()).toLong()
+            // If the recipe will produce more than we need, at it to the remaining
+            remaining[replacementRecipe.output.first] = (remaining[replacementRecipe.output.first] ?: 0L) + (replacementRecipeTimes * replacementRecipe.output.second) - inputRequiredAmount
+            val newInput = res.input.toMutableMap()
+            newInput.remove(ingredientToReplace)
+            replacementRecipe.input.entries.forEach { replacementIngredient ->
+
+                // Be greedy here: if the "remaining" for the replacement ingredient is enough to produce the recipe, we use it
+                // Shit...greedy appears to not be optimal for larger cases...
+                val replacementIngredientRemaining = remaining[replacementIngredient.key] ?: 0
+                val useRemainingTimes =
+                    min(replacementRecipeTimes, replacementIngredientRemaining / replacementIngredient.value)
+                if (useRemainingTimes > 0) {
+                    remaining[replacementIngredient.key] =
+                        remaining[replacementIngredient.key]!! - (useRemainingTimes * replacementIngredient.value)
+                }
+                newInput[replacementIngredient.key] = (newInput[replacementIngredient.key]
+                    ?: 0) + ((replacementRecipeTimes - useRemainingTimes) * replacementIngredient.value)
+
+            }
+
+            res = Recipe(newInput, res.output)
+        }
+        return res.input["ORE"] ?: error("Errore (hahah ore!)")
+    }
+
+    private fun calculateIngredientsRequired(ingredient: String, recipes: Map<String, Recipe>, cache: MutableMap<String, Set<String>>): Set<String> {
+
+        if (cache.containsKey(ingredient)) return cache[ingredient]!!
+
+        val res = mutableSetOf<String>()
+        val requiredIngredients = recipes[ingredient]?.input ?: return emptySet()
+        res.addAll(requiredIngredients.keys)
+        res.addAll(requiredIngredients.keys.flatMap { calculateIngredientsRequired(it, recipes, cache) })
+
+        cache[ingredient] = res
+
+        return res
+    }
+
+    data class Recipe(val input: Map<String, Long>, val output: Pair<String, Long>) {
+        companion object {
+
+            private val ingredientParser = Regex("^(\\d+)\\s+([A-Z]+)$")
+
+            fun parse(str: String): Recipe {
+                val split = str.split("=>").map { it.trim() }
+                val input = split[0].split(",")
+                    .map { parseIngredient(it) }
+                    .toMap()
+                val outputMatch = ingredientParser.matchEntire(split[1].trim())!!
+                val output = parseIngredient(split[1])
+                return Recipe(input, output)
+            }
+
+            private fun parseIngredient(str: String): Pair<String, Long> {
+                val match = ingredientParser.matchEntire(str.trim())!!
+                return Pair(match.groups[2]!!.value, match.groups[1]!!.value.toLong())
+            }
+        }
+    }
+}

src/main/resources/day/14/ex1.txt

@@ -0,0 +1,6 @@
+10 ORE => 10 A
+1 ORE => 1 B
+7 A, 1 B => 1 C
+7 A, 1 C => 1 D
+7 A, 1 D => 1 E
+7 A, 1 E => 1 FUEL

src/main/resources/day/14/ex2.txt

@@ -0,0 +1,7 @@
+9 ORE => 2 A
+8 ORE => 3 B
+7 ORE => 5 C
+3 A, 4 B => 1 AB
+5 B, 7 C => 1 BC
+4 C, 1 A => 1 CA
+2 AB, 3 BC, 4 CA => 1 FUEL

src/main/resources/day/14/ex3.txt

@@ -0,0 +1,9 @@
+157 ORE => 5 NZVS
+165 ORE => 6 DCFZ
+44 XJWVT, 5 KHKGT, 1 QDVJ, 29 NZVS, 9 GPVTF, 48 HKGWZ => 1 FUEL
+12 HKGWZ, 1 GPVTF, 8 PSHF => 9 QDVJ
+179 ORE => 7 PSHF
+177 ORE => 5 HKGWZ
+7 DCFZ, 7 PSHF => 2 XJWVT
+165 ORE => 2 GPVTF
+3 DCFZ, 7 NZVS, 5 HKGWZ, 10 PSHF => 8 KHKGT

src/main/resources/day/14/ex4.txt

@@ -0,0 +1,12 @@
+2 VPVL, 7 FWMGM, 2 CXFTF, 11 MNCFX => 1 STKFG
+17 NVRVD, 3 JNWZP => 8 VPVL
+53 STKFG, 6 MNCFX, 46 VJHF, 81 HVMC, 68 CXFTF, 25 GNMV => 1 FUEL
+22 VJHF, 37 MNCFX => 5 FWMGM
+139 ORE => 4 NVRVD
+144 ORE => 7 JNWZP
+5 MNCFX, 7 RFSQX, 2 FWMGM, 2 VPVL, 19 CXFTF => 3 HVMC
+5 VJHF, 7 MNCFX, 9 VPVL, 37 CXFTF => 6 GNMV
+145 ORE => 6 MNCFX
+1 NVRVD => 8 CXFTF
+1 VJHF, 6 MNCFX => 4 RFSQX
+176 ORE => 6 VJHF

src/main/resources/day/14/ex5.txt

@@ -0,0 +1,17 @@
+171 ORE => 8 CNZTR
+7 ZLQW, 3 BMBT, 9 XCVML, 26 XMNCP, 1 WPTQ, 2 MZWV, 1 RJRHP => 4 PLWSL
+114 ORE => 4 BHXH
+14 VRPVC => 6 BMBT
+6 BHXH, 18 KTJDG, 12 WPTQ, 7 PLWSL, 31 FHTLT, 37 ZDVW => 1 FUEL
+6 WPTQ, 2 BMBT, 8 ZLQW, 18 KTJDG, 1 XMNCP, 6 MZWV, 1 RJRHP => 6 FHTLT
+15 XDBXC, 2 LTCX, 1 VRPVC => 6 ZLQW
+13 WPTQ, 10 LTCX, 3 RJRHP, 14 XMNCP, 2 MZWV, 1 ZLQW => 1 ZDVW
+5 BMBT => 4 WPTQ
+189 ORE => 9 KTJDG
+1 MZWV, 17 XDBXC, 3 XCVML => 2 XMNCP
+12 VRPVC, 27 CNZTR => 2 XDBXC
+15 KTJDG, 12 BHXH => 5 XCVML
+3 BHXH, 2 VRPVC => 7 MZWV
+121 ORE => 7 VRPVC
+7 XCVML => 6 RJRHP
+5 BHXH, 4 VRPVC => 5 LTCX

src/main/resources/day/14/input.txt

@@ -0,0 +1,62 @@
+4 BFNQL => 9 LMCRF
+2 XGWNS, 7 TCRNC => 5 TPZCH
+4 RKHMQ, 1 QHRG, 5 JDSNJ => 4 XGWNS
+6 HWTBC, 4 XGWNS => 6 CWCD
+1 BKPZH, 2 FLZX => 9 HWFQG
+1 GDVD, 2 HTSW => 8 CNQW
+2 RMDG => 9 RKHMQ
+3 RTLHZ => 3 MSKWT
+1 QLNHG, 1 RJHCP => 3 GRDJ
+10 DLSD, 2 SWKHJ, 15 HTSW => 1 TCRNC
+4 SWKHJ, 24 ZHDSD, 2 DLSD => 3 CPGJ
+1 SWKHJ => 1 THJHK
+129 ORE => 8 KLSMQ
+3 SLNKW, 4 RTLHZ => 4 LPVGC
+1 SLNKW => 5 RLGFX
+2 QHRG, 1 SGMK => 8 RJHCP
+9 RGKCF, 7 QHRG => 6 ZHDSD
+8 XGWNS, 1 CPGJ => 2 QLNHG
+2 MQFJF, 7 TBVH, 7 FZXS => 2 WZMRW
+13 ZHDSD, 11 SLNKW, 18 RJHCP => 2 CZJR
+1 CNQW, 5 GRDJ, 3 GDVD => 4 FLZX
+129 ORE => 4 RHSHR
+2 HWTBC, 2 JDSNJ => 8 QPBHG
+1 BKPZH, 8 SWKHJ => 6 WSWBV
+8 RJHCP, 7 FRGJK => 1 GSDT
+6 QPBHG => 4 BKPZH
+17 PCRQV, 6 BFNQL, 9 GSDT, 10 MQDHX, 1 ZHDSD, 1 GRDJ, 14 BRGXB, 3 RTLHZ => 8 CFGK
+8 RMDG => 6 SGMK
+3 CZJR => 8 RTLHZ
+3 BFRTV => 7 RGKCF
+6 FRGJK, 8 CZJR, 4 GRDJ => 4 BRGXB
+4 VRVGB => 7 PCRQV
+4 TCRNC, 1 TBVH, 2 FZXS, 1 BQGM, 1 THJHK, 19 RLGFX => 2 CRJTJ
+5 RDNJK => 6 SWKHJ
+2 FLVC, 2 SLNKW, 30 HWTBC => 8 DLSD
+6 TBVH, 3 ZHDSD => 5 BQGM
+17 RLGFX => 4 SCZQN
+8 SWKHJ => 6 FZXS
+9 LZHZ => 3 QDCL
+2 ZHDSD => 1 RDNJK
+15 FZXS, 3 TPZCH => 6 MQFJF
+12 RLGFX, 9 QPBHG, 6 HTSW => 1 BFNQL
+150 ORE => 9 BFRTV
+2 BFRTV, 2 KLSMQ => 2 RMDG
+4 VFLNM, 30 RKHMQ, 4 CRJTJ, 24 CFGK, 21 SCZQN, 4 BMGBG, 9 HWFQG, 34 CWCD, 7 LPVGC, 10 QDCL, 2 WSWBV, 2 WTZX => 1 FUEL
+6 RHSHR, 3 RGKCF, 1 QHRG => 6 JDSNJ
+3 MQDHX, 2 XGWNS, 12 GRDJ => 9 LZHZ
+128 ORE => 6 ZBWLC
+9 JDSNJ, 7 RMDG => 8 FLVC
+4 DLSD, 12 CZJR, 3 MSKWT => 4 MQDHX
+2 BXNX, 4 ZBWLC => 3 QHRG
+19 LMCRF, 3 JDSNJ => 2 BMGBG
+1 RJHCP, 26 SGMK => 9 HTSW
+2 QPBHG => 8 VFLNM
+2 RGKCF => 9 SLNKW
+3 LZHZ, 2 GRDJ => 2 TBVH
+100 ORE => 2 BXNX
+4 DLSD, 21 JDSNJ => 8 GDVD
+2 QHRG => 2 HWTBC
+1 LPVGC, 8 XGWNS => 8 FRGJK
+9 FZXS => 7 VRVGB
+7 WZMRW, 1 TBVH, 1 VFLNM, 8 CNQW, 15 LZHZ, 25 PCRQV, 2 BRGXB => 4 WTZX