Day 14

14/answers.txt

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+431448
+3279311

14/input.txt

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+2 RWPCH => 9 PVTL
+1 FHFH => 4 BLPJK
+146 ORE => 5 VJNBT
+8 KDFNZ, 1 ZJGH, 1 GSCG => 5 LKPQG
+11 NWDZ, 2 WBQR, 1 VRQR => 2 BMJR
+3 GSCG => 4 KQDVM
+5 QVNKN, 6 RPWKC => 3 BCNV
+10 QMBM, 4 RBXB, 2 VRQR => 1 JHXBM
+15 RPWKC => 6 MGCQ
+1 QWKRZ => 4 FHFH
+10 RWPCH => 6 MZKG
+11 JFKGV, 5 QVNKN, 1 CTVK => 4 VQDT
+1 SXKT => 5 RPWKC
+1 VQDT, 25 ZVMCB => 2 RBXB
+6 LGLNV, 4 XSNKB => 3 WBQR
+199 ORE => 2 SXKT
+1 XSNKB, 6 CWBNX, 1 HPKB, 5 PVTL, 1 JNKH, 9 SXKT, 3 KQDVM => 3 ZKTX
+7 FDSX => 6 WJDF
+7 JLRM => 4 CWBNX
+167 ORE => 5 PQZXH
+13 JHXBM, 2 NWDZ, 4 RFLX, 12 VRQR, 10 FJRFG, 14 PVTL, 2 JLRM => 6 DGFG
+12 HPKB, 3 WHVXC => 9 ZJGH
+1 JLRM, 2 ZJGH, 2 QVNKN => 9 FJRFG
+129 ORE => 7 KZFPJ
+2 QMBM => 1 RWPCH
+7 VJMWM => 4 JHDW
+7 PQZXH, 7 SXKT => 9 BJVQM
+1 VJMWM, 4 JHDW, 1 MQXF => 7 FDSX
+1 RPWKC => 7 WHVXC
+1 ZJGH => 1 ZVMCB
+1 RWPCH => 3 MPKR
+187 ORE => 8 VJMWM
+15 CTVK => 5 GSCG
+2 XSNKB, 15 ZVMCB, 3 KDFNZ => 2 RFLX
+18 QVNKN => 8 XLFZJ
+4 CWBNX => 8 ZSCX
+2 ZJGH, 1 JLRM, 1 MGCQ => 9 NPRST
+13 BJVQM, 2 BCNV => 2 QWKRZ
+2 QWKRZ, 2 BLPJK, 5 XSNKB => 2 VRQR
+13 HPKB, 3 VQDT => 9 JLRM
+2 SXKT, 1 VJNBT, 5 VLWQB => 6 CTVK
+2 MPKR, 2 LMNCH, 24 VRQR => 8 DZFNW
+2 VQDT => 1 KDFNZ
+1 CTVK, 6 FDSX => 6 QVNKN
+3 CTVK, 1 QVNKN => 4 HPKB
+3 NPRST, 1 KGSDJ, 1 CTVK => 2 QMBM
+4 KZFPJ, 1 PQZXH => 5 VLWQB
+2 VQDT => 7 KGSDJ
+3 MPKR => 2 JNKH
+1 KQDVM => 5 XQBS
+3 ZKGMX, 1 XQBS, 11 MZKG, 11 NPRST, 1 DZFNW, 5 VQDT, 2 FHFH => 6 JQNF
+2 FJRFG, 17 BMJR, 3 BJVQM, 55 JQNF, 8 DGFG, 13 ZJGH, 29 ZKTX => 1 FUEL
+27 KZFPJ, 5 VJNBT => 5 MQXF
+11 FDSX, 1 WHVXC, 1 WJDF => 4 ZKGMX
+1 ZVMCB => 4 NWDZ
+1 XLFZJ => 6 LGLNV
+13 ZSCX, 4 XLFZJ => 8 LMNCH
+1 RPWKC, 1 FDSX, 2 BJVQM => 8 JFKGV
+1 WJDF, 1 LKPQG => 4 XSNKB

14/main.go

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+package main
+
+import (
+	"github.com/csmith/aoc-2019/common"
+	"math"
+	"strings"
+)
+
+type chemical string
+type recipeBook map[chemical]*recipe
+
+type amount struct {
+	chemical chemical
+	quantity int
+}
+
+type recipe struct {
+	produces *amount
+	requires []*amount
+}
+
+func parseAmount(text string) *amount {
+	parts := strings.Split(text, " ")
+	return &amount{
+		quantity: common.MustAtoi(parts[0]),
+		chemical: chemical(parts[1]),
+	}
+}
+
+func parseInput(file string) recipeBook {
+	recipes := make(map[chemical]*recipe)
+	for _, line := range common.ReadFileAsStrings(file) {
+		parts := strings.Split(line, " => ")
+		ingredients := strings.Split(parts[0], ", ")
+		r := &recipe{
+			produces: parseAmount(parts[1]),
+			requires: make([]*amount, 0, len(ingredients)),
+		}
+		for _, in := range ingredients {
+			r.requires = append(r.requires, parseAmount(in))
+		}
+		recipes[r.produces.chemical] = r
+	}
+	return recipes
+}
+
+func (rb recipeBook) produce(target *amount, used map[chemical]int, spare map[chemical]int) {
+	recipe := rb[target.chemical]
+	needed := target.quantity
+
+	if recipe == nil {
+		used[target.chemical] += needed
+		return
+	}
+
+	free := spare[target.chemical]
+	if free >= needed {
+		used[target.chemical] += needed
+		spare[target.chemical] -= needed
+		return
+	} else {
+		used[target.chemical] += free
+		spare[target.chemical] = 0
+		needed -= free
+	}
+
+	runs := int(math.Ceil(float64(needed) / float64(recipe.produces.quantity)))
+	for _, i := range recipe.requires {
+		rb.produce(&amount{
+			chemical: i.chemical,
+			quantity: i.quantity * runs,
+		}, used, spare)
+	}
+
+	used[target.chemical] += needed
+	spare[target.chemical] += (recipe.produces.quantity * runs) - needed
+}
+
+func main() {
+	recipes := parseInput("14/input.txt")
+	used := make(map[chemical]int, len(recipes))
+	spare := make(map[chemical]int, len(recipes))
+
+	recipes.produce(&amount{
+		chemical: "FUEL",
+		quantity: 1,
+	}, used, spare)
+
+	orePerFuel := used["ORE"]
+	println(used["ORE"])
+
+	last := 0
+	for used["ORE"] < 1000000000000 {
+		last = used["FUEL"]
+		recipes.produce(&amount{
+			chemical: "FUEL",
+			quantity: common.Max(1, (1000000000000-used["ORE"])/orePerFuel),
+		}, used, spare)
+	}
+
+	println(last)
+}