Move UnionFind to library

Author: sim642

src/main/scala/eu/sim642/adventofcode2025/Day8.scala

@@ -1,7 +1,8 @@
 package eu.sim642.adventofcode2025
 
 import eu.sim642.adventofcodelib.pos.Pos3
-import eu.sim642.adventofcodelib.IteratorImplicits._
+import eu.sim642.adventofcodelib.IteratorImplicits.*
+import eu.sim642.adventofcodelib.UnionFind
 
 import scala.annotation.tailrec
 
@@ -26,37 +27,6 @@ object Day8 {
       .map(_._1)
   }
 
-  class UnionFind[A](val reprs: Map[A, A]) {
-    // TODO: optimize
-
-    def this(items: Seq[A]) = {
-      this(items.map(x => x -> x).toMap)
-    }
-
-    @tailrec
-    final def findRepr(x: A): A = {
-      val repr = reprs(x)
-      if (x == repr)
-        repr
-      else
-        findRepr(repr)
-    }
-
-    def sameRepr(x: A, y: A): Boolean =
-      findRepr(x) == findRepr(y)
-
-    def unioned(x: A, y: A): UnionFind[A] = {
-      val xRepr = findRepr(x)
-      val yRepr = findRepr(y)
-      new UnionFind(reprs + (yRepr -> xRepr))
-    }
-
-    def groups(): Seq[Seq[A]] =
-      reprs.keys.groupBy(findRepr).values.map(_.toSeq).toSeq
-
-    override def toString: String = reprs.toString()
-  }
-
   def multiplySizesAfter(junctionBoxes: Seq[Pos3], after: Int = 1000, sizes: Int = 3): Int = {
     val closestPairs = closestPairsSeq(junctionBoxes)
 

src/main/scala/eu/sim642/adventofcodelib/UnionFind.scala

@@ -0,0 +1,34 @@
+package eu.sim642.adventofcodelib
+
+import scala.annotation.tailrec
+
+class UnionFind[A](val reprs: Map[A, A]) {
+  // TODO: optimize
+
+  def this(items: Seq[A]) = {
+    this(items.map(x => x -> x).toMap)
+  }
+
+  @tailrec
+  final def findRepr(x: A): A = {
+    val repr = reprs(x)
+    if (x == repr)
+      repr
+    else
+      findRepr(repr)
+  }
+
+  def sameRepr(x: A, y: A): Boolean =
+    findRepr(x) == findRepr(y)
+
+  def unioned(x: A, y: A): UnionFind[A] = {
+    val xRepr = findRepr(x)
+    val yRepr = findRepr(y)
+    new UnionFind(reprs + (yRepr -> xRepr))
+  }
+
+  def groups(): Seq[Seq[A]] =
+    reprs.keys.groupBy(findRepr).values.map(_.toSeq).toSeq
+
+  override def toString: String = reprs.toString()
+}