day15, example two

day15/dayFifteen.go

@@ -2,13 +2,18 @@ package day15
 
 import (
 	"fmt"
+	"log"
 	"os"
+	"regexp"
+	"slices"
+	"strconv"
 	"strings"
 )
 
 func Run() int {
 	fmt.Println("hello day 15")
-	filename := "day15/input"
+	log.Println("hello day 15")
+	filename := "day15/example"
 	bytes, err := os.ReadFile(filename)
 	if err != nil {
 		panic(fmt.Sprint("error reading file ", filename))
@@ -19,9 +24,116 @@ func Run() int {
 
 	result := 0
 
-	for _, instruction := range instructions {
-		result += ASCIIStringHash(instruction)
+	boxes := make([]Box, 256)
+	for i, box := range boxes {
+		box.Focals = make(map[string]int)
+		boxes[i] = box
 	}
+
+	for _, instructionStr := range instructions {
+		i := ReadInstruction(instructionStr)
+		box := boxes[i.Box]
+		box.Act(i)
+		boxes[i.Box] = box
+
+		// result += ASCIIStringHash(instruction)
+	}
+
+	for i, box := range boxes {
+		if len(box.Labels) != 0 {
+			log.Printf("%d box %+v final state\n", i, box)
+		}
+		result += (i + 1) * box.FocusingPower()
+	}
+
+	return result
+}
+
+type Box struct {
+	Labels []string
+	Focals map[string]int
+}
+
+func (b *Box)Act(i Instruction) {
+	log.Printf("for box %+v instruction \n%s\n", b, i.String())
+	switch i.Action {
+    case Put:
+		_, found := b.Focals[i.Label]
+		if !found {
+			b.Labels = append(b.Labels, i.Label)
+		}
+		b.Focals[i.Label] = i.LensFocal
+
+	case Remove:
+		_, found := b.Focals[i.Label]
+		if !found {
+			return
+		}
+		index := slices.Index(b.Labels, i.Label)
+		delete(b.Focals, i.Label)
+		b.Labels = slices.Delete(b.Labels, index, index+1)
+	}
+	log.Printf("result : %+v\n", b)
+	return
+}
+
+func (b *Box)FocusingPower() int {
+	result := 0
+	for i, label := range b.Labels {
+		result += (i + 1) * b.Focals[label]
+	}
+	return result
+}
+
+type Action rune
+
+const (
+	Put    Action = '='
+	Remove        = '-'
+)
+
+type Instruction struct {
+	Label     string
+	Box       int
+	Action    Action
+	LensFocal int
+}
+
+func (i *Instruction) String() string {
+	operation := ""
+	switch i.Action {
+	case Put:
+		operation = "put into"
+	case Remove:
+		operation = "remove from"
+	}
+	return fmt.Sprintf("%s\t\t%d of focal %d %s", operation, i.Box, i.LensFocal, i.Label)
+}
+
+func ReadInstruction(str string) Instruction {
+	result := Instruction{}
+
+	re := regexp.MustCompile(`(?P<label>\D+)(?P<operation>[=\-])(?P<focal>\d*)`)
+	// log.Println("in str ", str)
+	fields := re.FindStringSubmatch(str)
+	// log.Printf("in %s found %+v", str, fields)
+
+	operation := fields[2]
+	operationRune := []rune(operation)[0]
+	result.Action = Action(operationRune)
+
+	if operationRune == '=' {
+		focalStr := fields[3]
+		focal, err := strconv.Atoi(focalStr)
+		if err != nil {
+			panic(fmt.Sprint("error reading focal from ", str))
+		}
+		result.LensFocal = focal
+	}
+
+	result.Label = fields[1]
+	result.Box = ASCIIStringHash(result.Label)
+
 	return result
 }