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109 lines
2.2 KiB
109 lines
2.2 KiB
package main
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import (
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"os"
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"fmt"
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"strings"
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"strconv"
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)
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type input []string
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func parse(f string) (seq input) {
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seq = make(input, 0)
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for _, step := range strings.Split(f, ",") {
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step = strings.TrimSpace(step)
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seq = append(seq, step)
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}
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return
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}
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func hash(in string) (hash uint8) {
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hash = 0
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for _, byt := range []byte(in) {
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hash += byt
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hash *= 17
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}
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return
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}
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func part1(seq input) (sum uint) {
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for _, step := range seq { sum += uint(hash(step)) }
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return
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}
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type lens struct {
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label string
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focal uint64
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}
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func lens_find_label(arr []lens, label string) (pos int) {
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for pos, val := range arr{
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if val.label == label { return pos }
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}
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return -1
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}
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func part2(seq input) (sum uint64) {
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boxes := [256][]lens{}
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for i := 0; i < 256; i++ { boxes[i] = make([]lens, 0) }
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for _, step := range seq {
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var label string
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var op byte
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var off int
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if strings.Index(step, "=") >= 0 {
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off = strings.Index(step, "=")
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label = step[:off]
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op = step[off]
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} else if strings.Index(step, "-") >= 0 {
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off = strings.Index(step, "-")
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label = step[:off]
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op = step[off]
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}
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box := &boxes[hash(label)]
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pos := lens_find_label(*box, label)
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switch op {
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case '=':
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focal, _ := strconv.ParseUint(step[off + 1:], 0, 64)
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newlens := lens{
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label: label,
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focal: focal,
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}
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if pos >= 0 {
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(*box)[pos] = newlens
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} else {
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*box = append(*box, newlens)
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}
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case '-':
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if pos >= 0 {
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*box = append((*box)[:pos], (*box)[pos + 1:]...)
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}
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}
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}
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sum = 0
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for box_i, box := range boxes {
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for lens_i, lens := range box {
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fmt.Println(box_i + 1, ":", lens_i + 1, lens.label, lens.focal)
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sum += uint64(1 + box_i) * uint64(1 + lens_i) * lens.focal
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}
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}
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return
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}
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func main() {
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file, _ := os.ReadFile(os.Args[1])
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f := string(file)
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in := parse(f)
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fmt.Println(part1(in))
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fmt.Println(part2(in))
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}
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