2018 Complete!

2018/day25/constellation.go

@@ -0,0 +1,55 @@
+package main
+
+import "math"
+
+type Coordinate [4]int
+
+func (c Coordinate) Distance(b Coordinate) int {
+	sum := 0
+	for i := 0; i < 4; i++ {
+		sum += abs(c[i] - b[i])
+	}
+	return sum
+}
+
+type Constellation map[Coordinate]struct{}
+
+func (c Constellation) Distance(b Coordinate) int {
+	shortestDistance := math.MaxInt64
+
+	for p := range c {
+		if p.Distance(b) < shortestDistance {
+			shortestDistance = p.Distance(b)
+		}
+	}
+
+	return shortestDistance
+}
+
+func (c Constellation) CelestialDistance(b Constellation) int {
+	shortestDistance := math.MaxInt64
+
+	for p := range c {
+		if b.Distance(p) < shortestDistance {
+			shortestDistance = b.Distance(p)
+		}
+	}
+
+	return shortestDistance
+}
+
+func (c Constellation) Add(b Coordinate) {
+	c[b] = struct{}{}
+}
+
+func (c Constellation) Merge(b Constellation) {
+	for p := range b {
+		c[p] = struct{}{}
+		delete(b, p)
+	}
+}
+
+func NewConstellation(b Coordinate) Constellation {
+	c := Constellation{b: struct{}{}}
+	return c
+}

2018/day25/day25.go

@@ -2,146 +2,70 @@ package main
 
 import (
 	"bufio"
-	"errors"
 	"fmt"
-	"log"
-	"math"
 	"os"
-	"strconv"
-	"strings"
 )
 
-var grid *Grid
-
-// Pt 1
-// 431 too high
 func main() {
-	input := stdinToStringSlice()
-	grid = &Grid{}
-	for _, v := range input {
-		grid.addPoint(v)
+	inp := StdinToStringSlice()
+	fmt.Println(HotChocolatePortal(inp))
+}
+
+func HotChocolatePortal(input []string) int {
+	var constellations []Constellation
+
+	for _, line := range input {
+		var c Coordinate
+
+		if _, err := fmt.Sscanf(line, "%d,%d,%d,%d", &c[0], &c[1], &c[2], &c[3]); err != nil {
+			panic(err)
 		}
-	last := len(grid.constellations)
-	for grid.checkMerges() {
-		fmt.Println("++ merge ++ ", len(grid.constellations))
-		if len(grid.constellations) == last {
+
+		var found bool
+		for _, constellation := range constellations {
+			if constellation.Distance(c) <= 3 {
+				constellation.Add(c)
+				found = true
 				break
 			}
-		last = len(grid.constellations)
 		}
-	fmt.Println("Points:", len(grid.points))
-	fmt.Println("Constellations:", len(grid.constellations))
-}
+		if !found {
+			constellations = append(constellations, NewConstellation(c))
+		}
+	}
 
-type Grid struct {
-	points         []*Pos
-	constellations []*Constellation
-}
+	var nc []Constellation
+	for i, a := range constellations {
+		merged := false
 
-func (g *Grid) checkMerges() bool {
-	for ci, c := range g.constellations {
-		for _, p := range c.points {
-			for wrki, wrk := range g.constellations {
-				if wrki == ci {
+		for j, b := range constellations {
+			if i == j {
 				continue
 			}
-				if wrk.should(p) {
-					g.merge(ci, wrki)
-					g.remove(wrki)
-					return true
+
+			if b.CelestialDistance(a) <= 3 {
+				b.Merge(a)
+				merged = true
+				break
 			}
 		}
+
+		if !merged {
+			nc = append(nc, a)
 		}
 	}
-	fmt.Println("Nothing merged")
-	return false
+
+	return len(nc)
 }
 
-func (g *Grid) addPoint(inp string) {
-	pts := strings.Split(inp, ",")
-	pt := &Pos{
-		x: atoi(pts[0]),
-		y: atoi(pts[1]),
-		z: atoi(pts[2]),
-		t: atoi(pts[3]),
-	}
-	g.points = append(g.points, pt)
-
-	// Check if this point is within 3 from any other points
-	cIdx := -1
-	var mergedIdx []int
-	for i, v := range g.constellations {
-		if v.should(pt) {
-			if cIdx >= 0 {
-				g.merge(cIdx, i)
-				mergedIdx = append(mergedIdx, i)
-			} else {
-				cIdx = i
-				g.constellations[cIdx].add(pt)
-			}
-		}
-	}
-	for i := range mergedIdx {
-		g.remove(i)
-	}
-	if cIdx == -1 {
-		c := &Constellation{}
-		c.add(pt)
-		g.constellations = append(g.constellations, c)
+func abs(num int) int {
+	if num < 0 {
+		return num * -1
 	}
+	return num
 }
 
-func (g *Grid) merge(c1Idx, c2Idx int) error {
-	fmt.Println("  Merging", c1Idx, c2Idx)
-	if c1Idx >= len(g.constellations) || c2Idx >= len(g.constellations) {
-		return errors.New("Invalid Constellation Index")
-	}
-	for _, v := range g.constellations[c2Idx].points {
-		g.constellations[c1Idx].add(v)
-	}
-	return nil
-}
-
-func (g *Grid) remove(remIdx int) error {
-	if remIdx >= len(g.constellations) {
-		return errors.New("Invalid Constellation Index")
-	}
-	g.constellations = append(g.constellations[:remIdx], g.constellations[remIdx+1:]...)
-	return nil
-}
-
-type Constellation struct {
-	points []*Pos
-}
-
-func (c *Constellation) should(p *Pos) bool {
-	for _, v := range c.points {
-		if v.to(p) <= 3 {
-			return true
-		}
-	}
-	return false
-}
-
-func (c *Constellation) add(p *Pos) {
-	p.constellation = c
-	c.points = append(c.points, p)
-}
-
-type Pos struct {
-	x, y, z, t    int
-	constellation *Constellation
-}
-
-func (p *Pos) to(p2 *Pos) int {
-	xs := math.Abs(float64(p.x) - float64(p2.x))
-	ys := math.Abs(float64(p.y) - float64(p2.y))
-	zs := math.Abs(float64(p.z) - float64(p2.z))
-	ts := math.Abs(float64(p.t) - float64(p2.t))
-	return int(xs + ys + zs + ts)
-}
-
-func stdinToStringSlice() []string {
+func StdinToStringSlice() []string {
 	var input []string
 	scanner := bufio.NewScanner(os.Stdin)
 	for scanner.Scan() {
@@ -149,12 +73,3 @@ func stdinToStringSlice() []string {
 	}
 	return input
 }
-
-func atoi(i string) int {
-	var ret int
-	var err error
-	if ret, err = strconv.Atoi(i); err != nil {
-		log.Fatal("Invalid Atoi: " + i)
-	}
-	return ret
-}