feat: solve part one

internal/2025/DayEight/code.go

@@ -0,0 +1,156 @@
+package dayeight
+
+import (
+	"cmp"
+	"container/heap"
+	"os"
+	"slices"
+	"strconv"
+	"strings"
+
+	"advent-of-code/internal/registry"
+)
+
+func init() {
+	registry.Register("2025D8", ParseInput, PartOne, PartTwo)
+}
+
+type JunctionBox struct {
+	X, Y, Z int
+}
+
+type UnionFind struct {
+	parent []int
+	size   []int
+}
+
+type Connection struct {
+	firstJunctionBox, secondJunctionBox int
+	squaredDistance                     int
+}
+
+type ConnectionHeap []Connection
+
+func (h ConnectionHeap) Len() int           { return len(h) }
+func (h ConnectionHeap) Less(i, j int) bool { return h[i].squaredDistance > h[j].squaredDistance }
+func (h ConnectionHeap) Swap(i, j int)      { h[i], h[j] = h[j], h[i] }
+func (h *ConnectionHeap) Push(x any)        { *h = append(*h, x.(Connection)) }
+func (h *ConnectionHeap) Pop() any {
+	old := *h
+	n := len(old)
+	x := old[n-1]
+	*h = old[0 : n-1]
+	return x
+}
+
+func NewUnionFind(count int) *UnionFind {
+	parent := make([]int, count)
+	size := make([]int, count)
+	for idx := range parent {
+		parent[idx] = idx
+		size[idx] = 1
+	}
+	return &UnionFind{parent: parent, size: size}
+}
+
+func (uf *UnionFind) Find(junctionBox int) int {
+	if uf.parent[junctionBox] != junctionBox {
+		uf.parent[junctionBox] = uf.Find(uf.parent[junctionBox])
+	}
+	return uf.parent[junctionBox]
+}
+
+func (uf *UnionFind) Union(junctionBox1, junctionBox2 int) bool {
+	root1 := uf.Find(junctionBox1)
+	root2 := uf.Find(junctionBox2)
+	if root1 == root2 {
+		return false
+	}
+	if uf.size[root1] < uf.size[root2] {
+		root1, root2 = root2, root1
+	}
+	uf.parent[root2] = root1
+	uf.size[root1] += uf.size[root2]
+	return true
+}
+
+func ParseInput(filepath string) []string {
+	content, _ := os.ReadFile(filepath)
+	return strings.Split(string(content), "\n")
+}
+
+func PartOne(data []string) int {
+	var junctionBoxes []JunctionBox
+	for _, line := range data {
+		parts := strings.Split(line, ",")
+		x, _ := strconv.Atoi(parts[0])
+		y, _ := strconv.Atoi(parts[1])
+		z, _ := strconv.Atoi(parts[2])
+		junctionBoxes = append(junctionBoxes, JunctionBox{X: x, Y: y, Z: z})
+	}
+
+	junctionBoxCount := len(junctionBoxes)
+	targetPairs := 1000
+	if junctionBoxCount <= 20 {
+		targetPairs = 10
+	}
+
+	connectionHeap := make(ConnectionHeap, 0, targetPairs)
+	heap.Init(&connectionHeap)
+
+	for i := range junctionBoxCount {
+		for j := i + 1; j < junctionBoxCount; j++ {
+			dx := junctionBoxes[i].X - junctionBoxes[j].X
+			dy := junctionBoxes[i].Y - junctionBoxes[j].Y
+			dz := junctionBoxes[i].Z - junctionBoxes[j].Z
+			squaredDistance := dx*dx + dy*dy + dz*dz
+
+			connection := Connection{
+				firstJunctionBox:  i,
+				secondJunctionBox: j,
+				squaredDistance:   squaredDistance,
+			}
+
+			if len(connectionHeap) < targetPairs {
+				heap.Push(&connectionHeap, connection)
+			} else if connection.squaredDistance < connectionHeap[0].squaredDistance {
+				heap.Pop(&connectionHeap)
+				heap.Push(&connectionHeap, connection)
+			}
+		}
+	}
+
+	connections := make([]Connection, 0, len(connectionHeap))
+	for connectionHeap.Len() > 0 {
+		connections = append(connections, heap.Pop(&connectionHeap).(Connection))
+	}
+
+	slices.SortFunc(connections, func(a, b Connection) int {
+		return cmp.Compare(a.squaredDistance, b.squaredDistance)
+	})
+
+	uf := NewUnionFind(junctionBoxCount)
+	for _, connection := range connections {
+		uf.Union(connection.firstJunctionBox, connection.secondJunctionBox)
+	}
+
+	circuitSizes := make(map[int]int)
+	for idx := 0; idx < len(junctionBoxes); idx++ {
+		root := uf.Find(idx)
+		circuitSizes[root] = uf.size[root]
+	}
+
+	sizes := make([]int, 0, len(circuitSizes))
+	for _, size := range circuitSizes {
+		sizes = append(sizes, size)
+	}
+
+	slices.Sort(sizes)
+	slices.Reverse(sizes)
+
+	return sizes[0] * sizes[1] * sizes[2]
+}
+
+func PartTwo(data []string) int {
+	return 0
+}