149 lines
2.8 KiB
Go
149 lines
2.8 KiB
Go
package day15
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import (
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"fmt"
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"log"
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"os"
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"regexp"
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"slices"
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"strconv"
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"strings"
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)
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func Run() int {
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fmt.Println("hello day 15")
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log.Println("hello day 15")
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filename := "day15/example"
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bytes, err := os.ReadFile(filename)
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if err != nil {
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panic(fmt.Sprint("error reading file ", filename))
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}
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text := string(bytes)
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text = strings.TrimSpace(text)
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instructions := strings.Split(text, ",")
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result := 0
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boxes := make([]Box, 256)
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for i, box := range boxes {
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box.Focals = make(map[string]int)
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boxes[i] = box
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}
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for _, instructionStr := range instructions {
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i := ReadInstruction(instructionStr)
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box := boxes[i.Box]
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box.Act(i)
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boxes[i.Box] = box
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// result += ASCIIStringHash(instruction)
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}
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for i, box := range boxes {
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if len(box.Labels) != 0 {
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log.Printf("%d box %+v final state\n", i, box)
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}
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result += (i + 1) * box.FocusingPower()
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}
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return result
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}
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type Box struct {
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Labels []string
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Focals map[string]int
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}
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func (b *Box)Act(i Instruction) {
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log.Printf("for box %+v instruction \n%s\n", b, i.String())
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switch i.Action {
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case Put:
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_, found := b.Focals[i.Label]
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if !found {
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b.Labels = append(b.Labels, i.Label)
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}
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b.Focals[i.Label] = i.LensFocal
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case Remove:
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_, found := b.Focals[i.Label]
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if !found {
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return
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}
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index := slices.Index(b.Labels, i.Label)
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delete(b.Focals, i.Label)
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b.Labels = slices.Delete(b.Labels, index, index+1)
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}
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log.Printf("result : %+v\n", b)
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return
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}
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func (b *Box)FocusingPower() int {
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result := 0
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for i, label := range b.Labels {
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result += (i + 1) * b.Focals[label]
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}
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return result
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}
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type Action rune
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const (
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Put Action = '='
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Remove = '-'
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)
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type Instruction struct {
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Label string
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Box int
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Action Action
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LensFocal int
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}
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func (i *Instruction) String() string {
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operation := ""
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switch i.Action {
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case Put:
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operation = "put into"
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case Remove:
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operation = "remove from"
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}
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return fmt.Sprintf("%s\t\t%d of focal %d %s", operation, i.Box, i.LensFocal, i.Label)
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}
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func ReadInstruction(str string) Instruction {
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result := Instruction{}
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re := regexp.MustCompile(`(?P<label>\D+)(?P<operation>[=\-])(?P<focal>\d*)`)
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// log.Println("in str ", str)
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fields := re.FindStringSubmatch(str)
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// log.Printf("in %s found %+v", str, fields)
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operation := fields[2]
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operationRune := []rune(operation)[0]
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result.Action = Action(operationRune)
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if operationRune == '=' {
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focalStr := fields[3]
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focal, err := strconv.Atoi(focalStr)
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if err != nil {
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panic(fmt.Sprint("error reading focal from ", str))
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}
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result.LensFocal = focal
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}
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result.Label = fields[1]
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result.Box = ASCIIStringHash(result.Label)
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return result
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}
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func ASCIIStringHash(str string) int {
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result := 0
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for _, symb := range str {
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result += int(symb)
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result *= 17
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result %= 256
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}
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return result
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}
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