123 lines
2.1 KiB
Go
123 lines
2.1 KiB
Go
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package main
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import (
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"bufio"
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_ "embed"
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"fmt"
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"slices"
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"strings"
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aoc "go.sour.is/advent-of-code-2023"
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)
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var log = aoc.Log
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func main() { aoc.MustResult(aoc.Runner(run)) }
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type result struct {
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valuePT1 int
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valuePT2 int
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}
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func (r result) String() string { return fmt.Sprintf("%#v", r) }
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func run(scan *bufio.Scanner) (*result, error) {
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r := &result{}
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var ops []string
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for scan.Scan() {
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text := scan.Text()
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ops = strings.Split(text, ",")
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r.valuePT1 = aoc.Reduce(func(i int, t string, sum int) int {
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sum += hash(t)
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return sum
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}, 0, ops...)
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}
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var boxen boxes
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boxen = aoc.Reduce(func(i int, op string, b boxes) boxes {
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return b.Op(op)
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}, boxen, ops...)
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r.valuePT2 = boxen.Sum()
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log(boxen)
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return r, nil
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}
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func hash(s string) int {
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var sum int
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for _, a := range s {
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sum += int(a)
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sum *= 17
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sum %= 256
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}
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return sum
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}
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type lens struct {
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label string
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value int
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}
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type box []lens
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type boxes [256]box
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func (lis boxes) String() string {
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var buf strings.Builder
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buf.WriteString("Boxes:\n")
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for i, b := range lis {
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if len(b) > 0 {
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fmt.Fprintf(&buf, "Box %d: %v\n",i, b)
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}
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}
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return buf.String()
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}
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func (lis box) String() string {
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var buf strings.Builder
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if len(lis) > 0 {
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buf.WriteString(lis[0].String())
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}
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for _, l := range lis[1:] {
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buf.WriteString(l.String())
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}
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return buf.String()
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}
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func (l lens) String() string {
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return fmt.Sprintf("[%s %d]", l.label, l.value)
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}
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func (lis boxes) Op(op string) boxes {
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if a, _, ok := strings.Cut(op, "-"); ok {
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i := hash(a)
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pos := slices.IndexFunc(lis[i], func(l lens) bool { return l.label == a })
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if pos >= 0 {
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lis[i] = append(lis[i][:pos], lis[i][pos+1:]...)
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}
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} else if a, b, ok := strings.Cut(op, "="); ok {
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i := hash(a)
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pos := slices.IndexFunc(lis[i], func(l lens) bool { return l.label == a })
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v := aoc.Atoi(b)
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if pos == -1 {
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lis[i] = append(lis[i], lens{a, v})
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} else {
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lis[i][pos].value = v
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}
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}
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return lis
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}
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func (lis boxes) Sum() int {
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sum := 0
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for b := range lis {
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for s := range lis[b] {
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sum += (b+1) * (s+1) * lis[b][s].value
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}
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}
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return sum
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}
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