129 lines
2.1 KiB
Go
129 lines
2.1 KiB
Go
package main
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import (
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"fmt"
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"strings"
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h "git.bullercodeworks.com/brian/adventofcode/helpers"
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)
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func main() {
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inp := h.StdinToString()
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part1(inp)
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fmt.Println()
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part2(inp)
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}
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func part1(input string) {
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var res int
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pts := strings.Split(input, ",")
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for i := range pts {
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res += hash(pts[i])
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}
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fmt.Println("# Part 1")
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fmt.Println(res)
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}
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func part2(input string) {
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var boxes []*Box
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for i := 1; i <= 256; i++ {
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boxes = append(boxes, &Box{num: i})
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}
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for _, v := range strings.Split(input, ",") {
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l := NewLens(v)
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if l.focalLength == -1 {
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// Remove
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boxes[l.box].Remove(l)
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} else {
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// Add/Replace
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boxes[l.box].Add(l)
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}
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}
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var res int
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for i := range boxes {
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res += boxes[i].FocusingPower()
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}
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fmt.Println("# Part 2")
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fmt.Println(res)
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}
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type Box struct {
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num int
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lenses []*Lens
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}
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func (b *Box) Add(l *Lens) {
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for i := range b.lenses {
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if b.lenses[i].label == l.label {
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b.lenses[i] = l
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return
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}
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}
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b.lenses = append(b.lenses, l)
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}
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func (b *Box) Remove(l *Lens) {
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for i := range b.lenses {
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if b.lenses[i].label == l.label {
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b.lenses = append(b.lenses[:i], b.lenses[i+1:]...)
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return
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}
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}
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}
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func (b *Box) FocusingPower() int {
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var res int
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for i := range b.lenses {
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var lensRes int
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lensRes = b.num
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lensRes *= i + 1
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lensRes *= b.lenses[i].focalLength
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res += lensRes
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}
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return res
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}
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type Lens struct {
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label string
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focalLength int
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box int
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}
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func NewLens(inp string) *Lens {
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if strings.Contains(inp, "=") {
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pts := strings.Split(inp, "=")
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return &Lens{
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label: pts[0],
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focalLength: h.Atoi(pts[1]),
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box: hash(pts[0]),
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}
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} else {
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lbl := strings.TrimSuffix(inp, "-")
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return &Lens{
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label: lbl,
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focalLength: -1,
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box: hash(lbl),
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}
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}
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}
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func hash(inp string) int {
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var res int
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for _, i := range inp {
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res += int(i)
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res *= 17
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res = res % 256
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}
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return res
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}
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func focusingPower(lens string, boxNum int, boxes [][]string) int {
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res := boxNum + 1
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for i := 1; i <= len(boxes[boxNum]); i++ {
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if boxes[boxNum][i-1] == lens {
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res *= i
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break
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}
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}
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return res
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}
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