day-15

day-15/go.mod

@@ -0,0 +1,10 @@
+module github.com/onyx-and-iris/aoc2023/day-15
+
+go 1.21.5
+
+require (
+	github.com/elliotchance/orderedmap/v2 v2.2.0
+	github.com/sirupsen/logrus v1.9.3
+)
+
+require golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8 // indirect

day-15/go.sum

@@ -0,0 +1,18 @@
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/elliotchance/orderedmap/v2 v2.2.0 h1:7/2iwO98kYT4XkOjA9mBEIwvi4KpGB4cyHeOFOnj4Vk=
+github.com/elliotchance/orderedmap/v2 v2.2.0/go.mod h1:85lZyVbpGaGvHvnKa7Qhx7zncAdBIBq6u56Hb1PRU5Q=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/sirupsen/logrus v1.9.3 h1:dueUQJ1C2q9oE3F7wvmSGAaVtTmUizReu6fjN8uqzbQ=
+github.com/sirupsen/logrus v1.9.3/go.mod h1:naHLuLoDiP4jHNo9R0sCBMtWGeIprob74mVsIT4qYEQ=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.7.1 h1:5TQK59W5E3v0r2duFAb7P95B6hEeOyEnHRa8MjYSMTY=
+github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8 h1:0A+M6Uqn+Eje4kHMK80dtF3JCXC4ykBgQG4Fe06QRhQ=
+golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

day-15/hasher.go

@@ -0,0 +1,30 @@
+package main
+
+// hasher defines the methods required to hash a string
+type hasher struct {
+	next int
+}
+
+// newHasher returns a hasher type
+func newHasher() hasher {
+	return hasher{}
+}
+
+// run processes each step of the hasher for each char in a string
+func (h hasher) run(in string) int {
+	hash := 0
+	for _, r := range in {
+		h.next = hash + int(r)
+		hash = h.multiply().modulus()
+	}
+	return hash
+}
+
+func (h hasher) multiply() hasher {
+	h.next *= 17
+	return h
+}
+
+func (h hasher) modulus() int {
+	return h.next % 256
+}

day-15/makefile

@@ -0,0 +1,10 @@
+TEST="test.txt"
+INPUT="input.txt"
+
+test:
+	cat $(TEST) | go run .
+
+run:
+	cat $(INPUT) | go run .
+
+all: test

day-15/one.go

@@ -0,0 +1,18 @@
+package main
+
+import "strings"
+
+var lenses = []string{}
+
+// one returns the sum of all hashed values
+func one(lines []string) int {
+	lenses = strings.Split(lines[0], ",")
+	hash := newHasher()
+
+	sum := 0
+	for _, lense := range lenses {
+		sum += hash.run(lense)
+	}
+
+	return sum
+}

day-15/solution.go

@@ -0,0 +1,22 @@
+package main
+
+import (
+	"fmt"
+
+	log "github.com/sirupsen/logrus"
+)
+
+func init() {
+	log.SetLevel(log.DebugLevel)
+}
+
+func main() {
+	lines := readlines()
+
+	ans := one(lines)
+	fmt.Printf("solution one: %d\n", ans)
+
+	ans = two(lines)
+	fmt.Printf("solution two: %d\n", ans)
+
+}

day-15/two.go

@@ -0,0 +1,57 @@
+package main
+
+import (
+	"strings"
+
+	"github.com/elliotchance/orderedmap/v2"
+)
+
+var boxes = map[int]*orderedmap.OrderedMap[string, int]{}
+
+// add places a lense into an ordered box
+func add(id int, label string, focalLength int) {
+	boxes[id].Set(label, focalLength)
+}
+
+// remove takes a lense out of an ordered box
+func remove(id int, label string) {
+	boxes[id].Delete(strings.TrimRight(label, "-"))
+}
+
+// two returns the sum of all lense configurations
+func two(lines []string) int {
+	hash := newHasher()
+
+	for _, lense := range lenses {
+		label, focalLength := func() (string, int) {
+			x := strings.Split(lense, "=")
+			if len(x) == 2 {
+				return x[0], mustConv(x[1])
+			}
+			return strings.TrimRight(x[0], "-"), 0
+		}()
+		boxId := hash.run(label)
+
+		_, ok := boxes[boxId]
+		if !ok {
+			m := orderedmap.NewOrderedMap[string, int]()
+			boxes[boxId] = m
+		}
+
+		if strings.Contains(lense, "=") {
+			add(boxId, label, focalLength)
+		} else {
+			remove(boxId, label)
+		}
+	}
+
+	sum := 0
+	for id, box := range boxes {
+		for index, lense := range box.Keys() {
+			focalLength, _ := box.Get(lense)
+			sum += (id + 1) * (index + 1) * focalLength
+		}
+	}
+
+	return sum
+}

day-15/util.go

@@ -0,0 +1,35 @@
+package main
+
+import (
+	"bufio"
+	"log"
+	"os"
+	"strconv"
+)
+
+// readlines reads lines from stdin.
+// it returns them as an array of strings
+func readlines() []string {
+	lines := []string{}
+
+	scanner := bufio.NewScanner(os.Stdin)
+	for scanner.Scan() {
+		lines = append(lines, scanner.Text())
+	}
+
+	if err := scanner.Err(); err != nil {
+		log.Fatal(err)
+	}
+
+	return lines
+}
+
+// mustConv converts string to int
+// it will panic if an error occurs
+func mustConv(s string) int {
+	n, err := strconv.Atoi(s)
+	if err != nil {
+		panic(err)
+	}
+	return n
+}