2025 Day 8 Complete

2025/day08/main.go

@@ -0,0 +1,83 @@
+package main
+
+import (
+	"cmp"
+	"fmt"
+	"maps"
+	"slices"
+	"strings"
+
+	h "git.bullercodeworks.com/brian/adventofcode/helpers"
+)
+
+func main() {
+	inp := h.StdinToStringSlice()
+	solve(inp)
+}
+
+func solve(inp []string) {
+	var part1, part2 int
+	pts := inputToMap(inp)
+	circuits := []map[h.Coordinate3d]struct{}{}
+	for _, b := range pts {
+		circuits = append(circuits, map[h.Coordinate3d]struct{}{b: {}})
+	}
+
+	pairs := [][2]h.Coordinate3d{}
+	for i, b1 := range pts {
+		for _, b2 := range pts[i+1:] {
+			pairs = append(pairs, [2]h.Coordinate3d{b1, b2})
+		}
+	}
+	slices.SortFunc(pairs, func(a, b [2]h.Coordinate3d) int {
+		return cmp.Compare(a[0].Distance(a[1]), b[0].Distance(b[1]))
+	})
+
+	for i, p := range pairs {
+		var c1, c2 int
+		for i, c := range circuits {
+			if _, ok := c[p[0]]; ok {
+				c1 = i
+			}
+			if _, ok := c[p[1]]; ok {
+				c2 = i
+			}
+		}
+
+		if c1 != c2 {
+			maps.Copy(circuits[c1], circuits[c2])
+			circuits = slices.Delete(circuits, c2, c2+1)
+		}
+
+		if i+1 == 1000 {
+			slices.SortFunc(circuits, func(a, b map[h.Coordinate3d]struct{}) int {
+				return -cmp.Compare(len(a), len(b))
+			})
+			part1 = len(circuits[0]) * len(circuits[1]) * len(circuits[2])
+		}
+		if len(circuits) == 1 {
+			part2 = (p[0].X * p[1].X)
+			break
+		}
+	}
+	fmt.Println("# Part 1")
+	fmt.Println(part1)
+	fmt.Println()
+	fmt.Println("# Part 2")
+	fmt.Println(part2)
+}
+
+func inputToMap(inp []string) []h.Coordinate3d {
+	var ret []h.Coordinate3d
+	for i := range inp {
+		pts := strings.Split(inp[i], ",")
+		ret = append(ret,
+			h.Coordinate3d{
+				X: h.Atoi(pts[0]),
+				Y: h.Atoi(pts[1]),
+				Z: h.Atoi(pts[2]),
+			},
+		)
+	}
+	return ret
+}