day8 part1

day8/main.go

@@ -0,0 +1,128 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"slices"
+	"strconv"
+	"strings"
+
+	"github.com/dominikbraun/graph"
+)
+
+func readLines(filename string) []string {
+	raw, err := os.ReadFile(filename)
+	if err != nil {
+		panic(err)
+	}
+	return strings.Split(string(raw), "\n")
+}
+
+// input1 80446
+func main() {
+	filename := "input0.txt"
+	if len(os.Args) > 1 {
+		filename = os.Args[1]
+	}
+	lines := readLines(filename)
+	p := parsePlayground(lines)
+	circuits, err := p.wireClosest(1000)
+	if err != nil {
+		panic(err)
+	}
+	counts := map[uint]uint{}
+	for _, circuit := range circuits {
+		counts[circuit]++
+	}
+	totals := []uint{}
+	for _, v := range counts {
+		totals = append(totals, v)
+	}
+	slices.Sort(totals)
+	slices.Reverse(totals)
+	fmt.Printf("%v\n", totals[0]*totals[1]*totals[2])
+}
+
+func parsePlayground(lines []string) playground {
+	p := playground{
+		boxes:     []box{},
+		distances: graph.New(boxHash, graph.Weighted()),
+	}
+	for _, line := range lines {
+		parts := strings.Split(line, ",")
+		b := box{line: line}
+		b.x, _ = strconv.Atoi(parts[0])
+		b.y, _ = strconv.Atoi(parts[1])
+		b.z, _ = strconv.Atoi(parts[2])
+		_ = p.distances.AddVertex(b)
+		for _, c := range p.boxes {
+			_ = p.distances.AddEdge(b.line, c.line, graph.EdgeWeight(b.distanceTo(c)))
+		}
+		p.boxes = append(p.boxes, b)
+	}
+	return p
+}
+
+func (p *playground) wireClosest(n uint64) (map[string]uint, error) {
+	edges, err := p.distances.Edges()
+	if err != nil {
+		return nil, err
+	}
+	slices.SortFunc(edges, func(e1, e2 graph.Edge[string]) int {
+		return e1.Properties.Weight - e2.Properties.Weight
+	})
+	nextCircuit := uint(1)
+	circuits := map[string]uint{}
+	for i := range n {
+		edge := edges[i]
+		sourceCircuit := circuits[edge.Source]
+		targetCircuit := circuits[edge.Target]
+		if sourceCircuit == 0 && targetCircuit == 0 {
+			circuits[edge.Source] = nextCircuit
+			circuits[edge.Target] = nextCircuit
+			nextCircuit++
+			continue
+		}
+		if sourceCircuit == 0 {
+			circuits[edge.Source] = targetCircuit
+			continue
+		}
+		if targetCircuit == 0 {
+			circuits[edge.Target] = sourceCircuit
+			continue
+		}
+		if sourceCircuit == targetCircuit {
+			continue
+		}
+		for k, v := range circuits {
+			if v == targetCircuit {
+				circuits[k] = sourceCircuit
+			}
+		}
+	}
+	return circuits, nil
+}
+
+type playground struct {
+	boxes     []box
+	distances graph.Graph[string, box]
+}
+
+func boxHash(b box) string {
+	return b.line
+}
+
+type box struct {
+	line string
+	x    int
+	y    int
+	z    int
+}
+
+func (b box) distanceTo(c box) int {
+	x := c.x - b.x
+	y := c.y - b.y
+	z := c.z - b.z
+	// no need to sqrt since we only care about relative distances
+	return x*x + y*y + z*z
+}