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