Day 14 complete

days/14.go

@@ -2,6 +2,7 @@ package days
 
 import (
 	"fmt"
+	"math"
 	"strconv"
 	"strings"
 
@@ -21,7 +22,7 @@ type Day14 struct {
 func (d *Day14) Parse() {
 	d.leftovers = make(map[string]int)
 
-	lines := u.GetStringLines("14s2")
+	lines := u.GetStringLines("14p")
 	d.reactions = make([]reaction, len(lines))
 	for i, line := range lines {
 		sides := strings.Split(line, " => ")
@@ -53,97 +54,74 @@ func (d Day14) Num() int {
 	return 14
 }
 
-func (d Day14) getOreRequiredFor(chem string, amt int) (int, int) {
-	requiredOre := 0
-	for _, reaction := range d.reactions {
-		if reaction.output.First == chem {
-			// if oreAmt, exists := reaction.inputs["ORE"]; exists && len(reaction.inputs) == 1 {
-			// 	if d.leftovers[chem] >= amt {
-			// 		d.leftovers[chem] -= amt
-			// 		return 0, amt
-			// 	}
+func (d *Day14) oreRequiredStock(qty int64) int64 {
+	oreRequired := int64(0)
+	needs := map[string]int64{
+		"FUEL": qty,
+	}
+	excess := make(map[string]int64)
 
-			// 	produced := reaction.output.Second
-			// 	for produced < amt {
-			// 		requiredOre += oreAmt
-			// 		produced += reaction.output.Second
-			// 	}
-			// 	requiredOre += oreAmt
-			// 	if produced > amt {
-			// 		d.leftovers[chem] += produced - amt
-			// 	}
-			// 	return requiredOre, produced
-			// } else {
-			for inChem, inAmt := range reaction.inputs {
-				produced := 0
-				if d.leftovers[inChem] >= inAmt {
-					d.leftovers[inChem] -= inAmt
-					produced = inAmt
-				} else {
-					for produced < inAmt {
-						madeOre, madeChem := d.getOreRequiredFor(inChem, inAmt)
-						produced += madeChem
-						requiredOre += madeOre
-					}
-					if produced > inAmt {
-						d.leftovers[inChem] += produced - inAmt
-					}
-				}
+	getFromExcess := func(qty int64, chemical string) int64 {
+		inStock := excess[chemical]
+		qty -= inStock
+		excess[chemical] = int64(math.Min(math.Abs(float64(qty)), 0))
+		return inStock - excess[chemical]
+	}
+
+	for len(needs) > 0 {
+		keys := u.MapKeys(needs)
+		chemical := keys[len(keys)-1]
+		qtyRequired := needs[chemical]
+		delete(needs, chemical)
+
+		fromExcess := getFromExcess(qtyRequired, chemical)
+		qtyRequired -= fromExcess
+
+		reaction := d.getReactionProducing(chemical)
+		qtyProduced := int64(reaction.output.Second)
+		ingredients := reaction.inputs
+
+		n := int64(math.Ceil(float64(qtyRequired) / float64(qtyProduced)))
+
+		excess[chemical] = (qtyProduced * n) - qtyRequired
+		for ingredient, qtyIngredient := range ingredients {
+			if ingredient == "ORE" {
+				oreRequired += int64(int64(qtyIngredient) * n)
+			} else {
+				needs[ingredient] += int64(qtyIngredient) * n
 			}
-			// }
 		}
 	}
 
-	return requiredOre, 0
+	return oreRequired
 }
 
 func (d *Day14) Part1() string {
-	fuelReaction := d.getReactionProducing("FUEL")
-	if fuelReaction == nil {
-		panic("")
-	}
-
-	neededMaterial := map[string]int{
-		"FUEL": 1,
-	}
-	var recurse func(neededMaterial map[string]int) map[string]int
-	recurse = func(neededMaterial map[string]int) map[string]int {
-		neededInputs := make(map[string]int)
-		for chem, amt := range neededMaterial {
-			reaction := d.getReactionProducing(chem)
-			if reaction == nil {
-				continue
-			}
-			produced := reaction.output.Second
-			reactionsNeeded := 1
-			for produced < amt {
-				produced += reaction.output.Second
-				reactionsNeeded++
-			}
-			for inChem, inAmt := range reaction.inputs {
-				neededInputs[inChem] += inAmt * reactionsNeeded
-			}
-		}
-		if len(neededInputs) > 0 {
-			recursed := recurse(neededInputs)
-			for k, v := range recursed {
-				neededInputs[k] += v
-			}
-		}
-		return neededInputs
-	}
-	recursed := recurse(neededMaterial)
-	fmt.Println(len(recursed))
-
-	ore := 0
-	for inChem, inAmt := range fuelReaction.inputs {
-		requiredOre, _ := d.getOreRequiredFor(inChem, inAmt)
-		ore += requiredOre
-	}
-
-	return fmt.Sprintf("%s%d%s", u.TextBold, ore, u.TextReset)
+	neededOre := d.oreRequiredStock(1)
+	return fmt.Sprintf("%s%d%s", u.TextBold, neededOre, u.TextReset)
 }
 
 func (d *Day14) Part2() string {
-	return ""
+	oreAvailable := int64(1000000000000)
+	estimate := oreAvailable / d.oreRequiredStock(1)
+
+	high := estimate * 2
+	low := estimate
+
+	lastSuccess := low
+	lastFailure := high
+	fuelProduced := low
+
+	for math.Abs(float64(lastFailure)-float64(lastSuccess)) > 1 {
+		oreConsumed := d.oreRequiredStock(fuelProduced)
+		if oreConsumed < oreAvailable {
+			lastSuccess = fuelProduced
+			fuelProduced += (lastFailure - lastSuccess) / 2
+		} else {
+			lastFailure = fuelProduced
+			fuelProduced -= (lastFailure - lastSuccess) / 2
+		}
+	}
+
+	return fmt.Sprintf("%s%d%s", u.TextBold, lastSuccess, u.TextReset)
 }

utilities/map.go

@@ -0,0 +1,17 @@
+package utilities
+
+func MapKeys[T comparable, U any](m map[T]U) []T {
+	r := make([]T, 0, len(m))
+	for k := range m {
+		r = append(r, k)
+	}
+	return r
+}
+
+func MapValues[T comparable, U any](m map[T]U) []U {
+	r := make([]U, 0, len(m))
+	for _, v := range m {
+		r = append(r, v)
+	}
+	return r
+}