question 8 (question 8B does not work but I am tired)
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@@ -0,0 +1,299 @@
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package main
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import (
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"fmt"
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"math/big"
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"strings"
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)
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type Map struct {
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data []rune
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width int
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height int
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}
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type Point struct {
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x, y int
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}
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func (p *Point) String() string {
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return fmt.Sprintf("(%d, %d)", p.x, p.y)
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}
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func (p *Point) IsBetween(p1 *Point, p2 *Point) bool {
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return isBetween(p.x, p1.x, p2.x) && isBetween(p.y, p1.y, p2.y)
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}
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// Returns true is a is between (x, y) disregarding
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// x, y order ( (x,y) is considered an interval.
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// The definition of between includes both ends
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func isBetween(a int, x int, y int) bool {
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if x > y {
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return isBetween(a, y, x)
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}
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return x <= a && a <= y
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}
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func (p *Point) Dist(p2 *Point) *Vector {
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return NewVecFromInt(p2.x-p.x, p2.y-p.y)
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}
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func NewVecFromInt(x, y int) *Vector {
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return &Vector{big.NewRat(int64(x), 1), big.NewRat(int64(y), 1)}
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}
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type Vector struct {
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x, y *big.Rat
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}
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func (v *Vector) String() string {
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return fmt.Sprintf("(%s, %s)", v.x, v.y)
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}
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func (v *Vector) Time(n *big.Rat) *Vector {
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return &Vector{new(big.Rat).Mul(v.x, n), new(big.Rat).Mul(v.y, n)}
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}
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func (v *Vector) Opp() *Vector {
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return v.Time(big.NewRat(-1, 1))
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}
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func (v *Vector) Plus(vec2 *Vector) *Vector {
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return &Vector{new(big.Rat).Add(v.x, vec2.x), new(big.Rat).Add(v.y, vec2.y)}
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}
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func (v *Vector) AsPoint() *Point {
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if !v.x.IsInt() || !v.y.IsInt() {
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panic("Not a point")
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}
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return &Point{int(v.x.Num().Int64()), int(v.y.Num().Int64())}
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}
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func BaryCenter(p1, p2 *Point) *Vector {
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return &Vector{
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big.NewRat(int64(p1.x+p2.x), 2),
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big.NewRat(int64(p1.y+p2.y), 2),
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}
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}
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func (m *Map) isInbound(point *Point) bool {
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return point.x >= 0 && point.x < m.width && point.y >= 0 && point.y < m.width
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}
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func (m *Map) Get(point *Point) (rune, bool) {
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if !m.isInbound(point) {
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return 0, false
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}
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idx := point.x + m.width*point.y
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return m.data[idx], true
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}
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func (m *Map) getByDataIndex(idx int) *Point {
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x := idx % m.width
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y := idx / m.width
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return &Point{x, y}
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}
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func NewMap(input string) *Map {
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if !strings.HasSuffix(input, "\n") {
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input += "\n"
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}
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width := strings.Index(input, "\n")
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height := strings.Count(input, "\n")
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data := []rune(strings.ReplaceAll(input, "\n", ""))
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return &Map{data, width, height}
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}
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func (m *Map) getAllAntennaFrequencies() <-chan rune {
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ch := make(chan rune)
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go func() {
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dejaVu := make(map[rune]bool)
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dejaVu['.'] = true
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for _, r := range m.data {
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if _, ok := dejaVu[r]; !ok {
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dejaVu[r] = true
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ch <- r
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}
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}
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close(ch)
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}()
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return ch
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}
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func (m *Map) getAllAntennaOfFrequency(freq rune) []*Point {
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ret := make([]*Point, 0)
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for i, r := range m.data {
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if r == freq {
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ret = append(ret, m.getByDataIndex(i))
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}
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}
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return ret
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}
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type AntennaPair struct {
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antenna1 *Point
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antenna2 *Point
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freq rune
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}
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func (m *Map) getAllAntennaPairsOfFrequency(freq rune) <-chan *AntennaPair {
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antennas := m.getAllAntennaOfFrequency(freq)
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ch := make(chan *AntennaPair)
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go func() {
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for i := 0; i < len(antennas); i++ {
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for j := i + 1; j < len(antennas); j++ {
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ch <- &AntennaPair{antennas[i], antennas[j], freq}
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}
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}
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close(ch)
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}()
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return ch
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}
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func (m *Map) getEquidistantAntinodeLocationsForFreq(freq rune) <-chan *Point {
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ch := make(chan *Point)
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go func() {
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for p := range m.getAllAntennaPairsOfFrequency(freq) {
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bc := BaryCenter(p.antenna1, p.antenna2)
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dist := p.antenna1.Dist(p.antenna2).Time(big.NewRat(3, 2))
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antiNode1 := bc.Plus(dist).AsPoint()
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antiNode2 := bc.Plus(dist.Opp()).AsPoint()
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if m.isInbound(antiNode1) {
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ch <- antiNode1
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}
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if m.isInbound(antiNode2) {
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ch <- antiNode2
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}
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}
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close(ch)
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}()
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return ch
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}
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func (m *Map) generateInlinePoints(p *Point, stepX, stepY int, filter func(*Point) bool, ch chan<- *Point) {
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for {
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p = &Point{p.x + stepX, p.y + stepY}
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if !m.isInbound(p) {
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return
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}
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if filter(p) {
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ch <- p
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}
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}
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}
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func (m *Map) getStep(p *AntennaPair) (int, int) {
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dist := p.antenna1.Dist(p.antenna2)
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if dist.x.Cmp(big.NewRat(0, 1)) == 0 {
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return 0, 1
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}
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if dist.y.Cmp(big.NewRat(0, 1)) == 0 {
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return 1, 0
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}
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step := new(big.Rat).Quo(dist.y, dist.x)
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stepX := int(step.Denom().Int64())
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stepY := int(step.Num().Int64())
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if stepX < 0 {
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stepX = -stepX
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}
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return stepX, stepY
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}
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func (m *Map) getCollinearAntinodeLocationsFreq(freq rune) <-chan *Point {
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ch := make(chan *Point)
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go func() {
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for pair := range m.getAllAntennaPairsOfFrequency(freq) {
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stepX, stepY := m.getStep(pair)
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filter := func(p *Point) bool {
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return !p.IsBetween(pair.antenna1, pair.antenna2)
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}
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m.generateInlinePoints(pair.antenna1, stepX, stepY, filter, ch)
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m.generateInlinePoints(pair.antenna1, -stepX, -stepY, filter, ch)
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}
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close(ch)
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}()
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return ch
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}
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func dedupPoints(points <-chan *Point) <-chan *Point {
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ch := make(chan *Point)
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go func() {
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m := make(map[int]map[int]bool)
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for p := range points {
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if _, ok := m[p.x]; ok {
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if _, ok2 := m[p.x][p.y]; ok2 {
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continue
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}
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m[p.x][p.y] = true
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} else {
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m[p.x] = make(map[int]bool)
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m[p.x][p.y] = true
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}
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ch <- p
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}
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close(ch)
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}()
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return ch
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}
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func (m *Map) getAllEquidistantAntinodeLocations() <-chan *Point {
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ch := make(chan *Point)
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go func() {
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for freq := range m.getAllAntennaFrequencies() {
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for p := range m.getEquidistantAntinodeLocationsForFreq(freq) {
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ch <- p
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}
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}
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close(ch)
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}()
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return dedupPoints(ch)
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}
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func (m *Map) getAllCollinearAntinodeLocations() <-chan *Point {
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ch := make(chan *Point)
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go func() {
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for freq := range m.getAllAntennaFrequencies() {
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for p := range m.getCollinearAntinodeLocationsFreq(freq) {
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ch <- p
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}
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}
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close(ch)
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}()
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return dedupPoints(ch)
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}
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func question8A(input string) int {
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i := 0
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m := NewMap(input)
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for _ = range m.getAllEquidistantAntinodeLocations() {
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i++
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}
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return i
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}
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func question8B(input string) int {
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i := 0
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m := NewMap(input)
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for _ = range m.getAllCollinearAntinodeLocations() {
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//fmt.Println(">> ", p)
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i++
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}
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return i
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}
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func main() {
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fmt.Printf("The answer to question 8A is %d \n", question8A(realInput))
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fmt.Printf("The answer to question 8B is %d \n", question8B(mockInput))
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}
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