Implement the Traverser

Author: ForNeVeR

src/main/scala/ru/org/codingteam/icfpc_2025/Traverser.scala

@@ -0,0 +1,28 @@
+package ru.org.codingteam.icfpc_2025
+
+object Traverser:
+    def traverse(solution: SolutionDefinition, route: Seq[Int]): Seq[Int] =
+        var currentRoomIndex = solution.startingRoom
+        var result = List(solution.rooms(currentRoomIndex))
+        for (openDoor <- route)
+            val fromConnection = solution.connections
+                .filter { conn => conn.from.room == currentRoomIndex && conn.from.door == openDoor }
+                .toVector
+            val toConnection = solution.connections
+                .filter { conn => conn.to.room == currentRoomIndex && conn.to.door == openDoor }
+                .toVector
+
+            if (fromConnection.size > 1 || toConnection.size > 1)
+                throw new Exception(s"Invalid solution: found more than one connection for door $openDoor in room $currentRoomIndex.")
+
+            if (fromConnection.nonEmpty && toConnection.nonEmpty && fromConnection.head != toConnection.head)
+                throw new Exception(s"Invalid solution: connection $fromConnection does not match $toConnection (room $currentRoomIndex, door $openDoor).")
+
+            if (fromConnection.isEmpty && toConnection.isEmpty)
+                throw new Exception(s"Invalid solution: cannot find a door $openDoor in room $currentRoomIndex.")
+
+            val connection = if fromConnection.nonEmpty then fromConnection.head else toConnection.head
+            currentRoomIndex = if connection.from.room == currentRoomIndex then connection.to.room else connection.from.room
+            result = currentRoomIndex :: result
+
+        result.reverse

src/test/scala/ru/org/codingteam/icfpc_2025/TraverserTests.scala

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+package ru.org.codingteam.icfpc_2025
+
+import org.scalatest.funsuite.AnyFunSuite
+
+class TraverserTests extends AnyFunSuite:
+
+    test("simple route") {
+        val solution = SolutionDefinition(
+            Vector(0, 1, 2),
+            0,
+            Vector(
+                ConnectionDefinition(Door(0, 0), Door(1, 0)),
+                ConnectionDefinition(Door(1, 1), Door(2, 1)),
+                ConnectionDefinition(Door(2, 2), Door(0, 2))
+            )
+        )
+        val route = Seq(0, 1, 2)
+        val result = Traverser.traverse(solution, route)
+        assert(result == Seq(0, 1, 2, 0))
+    }