Import quickcheck handout

.vscode/settings.json

@@ -0,0 +1,8 @@
+{
+  "dotty": {
+    "trace": {
+      "remoteTracingUrl": "wss://lamppc36.epfl.ch/dotty-remote-tracer/upload/lsp.log",
+      "server": { "format": "JSON", "verbosity": "verbose" }
+    }
+  }
+}

build.sbt

@@ -0,0 +1,11 @@
+course := "progfun2"
+assignment := "quickcheck"
+name := course.value + "-" + assignment.value
+testSuite := "quickcheck.QuickCheckSuite"
+
+scalaVersion := "0.19.0-RC1"
+scalacOptions ++= Seq("-language:implicitConversions", "-deprecation")
+libraryDependencies += "com.novocode" % "junit-interface" % "0.11" % Test
+libraryDependencies += ("org.scalacheck" %% "scalacheck" % "1.14.2").withDottyCompat(scalaVersion.value)
+
+testOptions in Test += Tests.Argument(TestFrameworks.JUnit, "-a", "-v", "-s")

project/MOOCSettings.scala

@@ -0,0 +1,25 @@
+package ch.epfl.lamp
+
+import sbt._
+import sbt.Keys._
+
+/**
+  * Settings shared by all assignments, reused in various tasks.
+  */
+object MOOCSettings extends AutoPlugin {
+
+  object autoImport {
+    val course = SettingKey[String]("course")
+    val assignment = SettingKey[String]("assignment")
+    val testSuite = SettingKey[String]("testSuite")
+    val options = SettingKey[Map[String, Map[String, String]]]("options")
+  }
+
+  override def trigger = allRequirements
+
+  override val projectSettings: Seq[Def.Setting[_]] = Seq(
+    parallelExecution in Test := false,
+    // Report test result after each test instead of waiting for every test to finish
+    logBuffered in Test := false
+  )
+}

project/StudentTasks.scala

@@ -0,0 +1,323 @@
+package ch.epfl.lamp
+
+import sbt._
+import Keys._
+
+// import scalaj.http._
+import java.io.{File, FileInputStream, IOException}
+import java.nio.file.FileSystems
+import org.apache.commons.codec.binary.Base64
+// import play.api.libs.json.{Json, JsObject, JsPath}
+import scala.util.{Failure, Success, Try}
+
+import MOOCSettings.autoImport._
+
+case class AssignmentInfo(
+  key: String,
+  itemId: String,
+  premiumItemId: Option[String],
+  partId: String
+)
+
+/**
+  * Provides tasks for submitting the assignment
+  */
+object StudentTasks extends AutoPlugin {
+
+  object autoImport {
+    val assignmentInfo = SettingKey[AssignmentInfo]("assignmentInfo")
+
+    val packageSourcesOnly = TaskKey[File]("packageSourcesOnly", "Package the sources of the project")
+    val packageBinWithoutResources = TaskKey[File]("packageBinWithoutResources", "Like packageBin, but without the resources")
+    val packageSubmissionZip = TaskKey[File]("packageSubmissionZip")
+    val packageSubmission = inputKey[Unit]("package solution as an archive file")
+    val runGradingTests = taskKey[Unit]("run black-box tests used for final grading")
+  }
+
+
+  import autoImport._
+
+  override lazy val projectSettings = Seq(
+    packageSubmissionSetting,
+    // submitSetting, // FIXME: restore assignmentInfo setting on assignments
+    runGradingTestsSettings,
+
+    fork := true,
+    connectInput in run := true,
+    outputStrategy := Some(StdoutOutput)
+  ) ++ packageSubmissionZipSettings
+
+  lazy val runGradingTestsSettings = runGradingTests := {
+    val testSuiteJar = "grading-tests.jar"
+    if (!new File(testSuiteJar).exists) {
+      throw new MessageOnlyException(s"Could not find tests JarFile: $testSuiteJar")
+    }
+
+    val classPath = s"${(Test / dependencyClasspath).value.map(_.data).mkString(File.pathSeparator)}${File.pathSeparator}$testSuiteJar"
+    val junitProcess =
+      Fork.java.fork(
+        ForkOptions(),
+        "-cp" :: classPath ::
+        "org.junit.runner.JUnitCore" ::
+        (Test / testSuite).value ::
+        Nil
+      )
+
+    // Wait for tests to complete.
+    junitProcess.exitValue()
+  }
+
+
+  /** **********************************************************
+    * SUBMITTING A SOLUTION TO COURSERA
+    */
+
+  val packageSubmissionZipSettings = Seq(
+    packageSubmissionZip := {
+      val submission = crossTarget.value / "submission.zip"
+      val sources = (packageSourcesOnly in Compile).value
+      val binaries = (packageBinWithoutResources in Compile).value
+      IO.zip(Seq(sources -> "sources.zip", binaries -> "binaries.jar"), submission)
+      submission
+    },
+    artifactClassifier in packageSourcesOnly := Some("sources"),
+    artifact in (Compile, packageBinWithoutResources) ~= (art => art.withName(art.name + "-without-resources"))
+  ) ++
+  inConfig(Compile)(
+    Defaults.packageTaskSettings(packageSourcesOnly, Defaults.sourceMappings) ++
+    Defaults.packageTaskSettings(packageBinWithoutResources, Def.task {
+      val relativePaths =
+        (unmanagedResources in Compile).value.flatMap(Path.relativeTo((unmanagedResourceDirectories in Compile).value)(_))
+      (mappings in (Compile, packageBin)).value.filterNot { case (_, path) => relativePaths.contains(path) }
+    })
+  )
+
+  val maxSubmitFileSize = {
+    val mb = 1024 * 1024
+    10 * mb
+  }
+
+  /** Check that the jar exists, isn't empty, isn't crazy big, and can be read
+    * If so, encode jar as base64 so we can send it to Coursera
+    */
+  def prepareJar(jar: File, s: TaskStreams): String = {
+    val errPrefix = "Error submitting assignment jar: "
+    val fileLength = jar.length()
+    if (!jar.exists()) {
+      s.log.error(errPrefix + "jar archive does not exist\n" + jar.getAbsolutePath)
+      failSubmit()
+    } else if (fileLength == 0L) {
+      s.log.error(errPrefix + "jar archive is empty\n" + jar.getAbsolutePath)
+      failSubmit()
+    } else if (fileLength > maxSubmitFileSize) {
+      s.log.error(errPrefix + "jar archive is too big. Allowed size: " +
+        maxSubmitFileSize + " bytes, found " + fileLength + " bytes.\n" +
+        jar.getAbsolutePath)
+      failSubmit()
+    } else {
+      val bytes = new Array[Byte](fileLength.toInt)
+      val sizeRead = try {
+        val is = new FileInputStream(jar)
+        val read = is.read(bytes)
+        is.close()
+        read
+      } catch {
+        case ex: IOException =>
+          s.log.error(errPrefix + "failed to read sources jar archive\n" + ex.toString)
+          failSubmit()
+      }
+      if (sizeRead != bytes.length) {
+        s.log.error(errPrefix + "failed to read the sources jar archive, size read: " + sizeRead)
+        failSubmit()
+      } else encodeBase64(bytes)
+    }
+  }
+
+  /** Task to package solution to a given file path */
+  lazy val packageSubmissionSetting = packageSubmission := {
+    val args: Seq[String] = Def.spaceDelimited("[path]").parsed
+    val s: TaskStreams = streams.value // for logging
+    val jar = (packageSubmissionZip in Compile).value
+
+    val base64Jar = prepareJar(jar, s)
+
+    val path = args.headOption.getOrElse((baseDirectory.value / "submission.jar").absolutePath)
+    scala.tools.nsc.io.File(path).writeAll(base64Jar)
+  }
+
+/*
+  /** Task to submit a solution to coursera */
+  val submit = inputKey[Unit]("submit solution to Coursera")
+  lazy val submitSetting = submit := {
+    val args: Seq[String] = Def.spaceDelimited("<arg>").parsed
+    val s: TaskStreams = streams.value // for logging
+    val jar = (packageSubmissionZip in Compile).value
+
+    val assignmentDetails = assignmentInfo.value
+    val assignmentKey = assignmentDetails.key
+    val courseName =
+      course.value match {
+        case "capstone" => "scala-capstone"
+        case "bigdata"  => "scala-spark-big-data"
+        case other      => other
+      }
+
+    val partId = assignmentDetails.partId
+    val itemId = assignmentDetails.itemId
+    val premiumItemId = assignmentDetails.premiumItemId
+
+    val (email, secret) = args match {
+      case email :: secret :: Nil =>
+        (email, secret)
+      case _ =>
+        val inputErr =
+          s"""|Invalid input to `submit`. The required syntax for `submit` is:
+              |submit <email-address> <submit-token>
+              |
+              |The submit token is NOT YOUR LOGIN PASSWORD.
+              |It can be obtained from the assignment page:
+              |https://www.coursera.org/learn/$courseName/programming/$itemId
+              |${
+                premiumItemId.fold("") { id =>
+                  s"""or (for premium learners):
+                     |https://www.coursera.org/learn/$courseName/programming/$id
+                   """.stripMargin
+                }
+              }
+          """.stripMargin
+        s.log.error(inputErr)
+        failSubmit()
+    }
+
+    val base64Jar = prepareJar(jar, s)
+    val json =
+      s"""|{
+          |   "assignmentKey":"$assignmentKey",
+          |   "submitterEmail":"$email",
+          |   "secret":"$secret",
+          |   "parts":{
+          |      "$partId":{
+          |         "output":"$base64Jar"
+          |      }
+          |   }
+          |}""".stripMargin
+
+    def postSubmission[T](data: String): Try[HttpResponse[String]] = {
+      val http = Http("https://www.coursera.org/api/onDemandProgrammingScriptSubmissions.v1")
+      val hs = List(
+        ("Cache-Control", "no-cache"),
+        ("Content-Type", "application/json")
+      )
+      s.log.info("Connecting to Coursera...")
+      val response = Try(http.postData(data)
+                         .headers(hs)
+                         .option(HttpOptions.connTimeout(10000)) // scalaj default timeout is only 100ms, changing that to 10s
+                         .asString) // kick off HTTP POST
+      response
+    }
+
+    val connectMsg =
+      s"""|Attempting to submit "${assignment.value}" assignment in "$courseName" course
+          |Using:
+          |- email: $email
+          |- submit token: $secret""".stripMargin
+    s.log.info(connectMsg)
+
+    def reportCourseraResponse(response: HttpResponse[String]): Unit = {
+      val code = response.code
+      val respBody = response.body
+
+       /* Sample JSON response from Coursera
+      {
+        "message": "Invalid email or token.",
+        "details": {
+          "learnerMessage": "Invalid email or token."
+        }
+      }
+      */
+
+      // Success, Coursera responds with 2xx HTTP status code
+      if (response.is2xx) {
+        val successfulSubmitMsg =
+          s"""|Successfully connected to Coursera. (Status $code)
+              |
+                |Assignment submitted successfully!
+              |
+                |You can see how you scored by going to:
+              |https://www.coursera.org/learn/$courseName/programming/$itemId/
+              |${
+            premiumItemId.fold("") { id =>
+              s"""or (for premium learners):
+                 |https://www.coursera.org/learn/$courseName/programming/$id
+                       """.stripMargin
+            }
+          }
+              |and clicking on "My Submission".""".stripMargin
+        s.log.info(successfulSubmitMsg)
+      }
+
+      // Failure, Coursera responds with 4xx HTTP status code (client-side failure)
+      else if (response.is4xx) {
+        val result = Try(Json.parse(respBody)).toOption
+        val learnerMsg = result match {
+          case Some(resp: JsObject) =>
+            (JsPath \ "details" \ "learnerMessage").read[String].reads(resp).get
+          case Some(x) => // shouldn't happen
+            "Could not parse Coursera's response:\n" + x
+          case None =>
+            "Could not parse Coursera's response:\n" + respBody
+        }
+        val failedSubmitMsg =
+          s"""|Submission failed.
+              |There was something wrong while attempting to submit.
+              |Coursera says:
+              |$learnerMsg (Status $code)""".stripMargin
+        s.log.error(failedSubmitMsg)
+      }
+
+      // Failure, Coursera responds with 5xx HTTP status code (server-side failure)
+      else if (response.is5xx) {
+        val failedSubmitMsg =
+          s"""|Submission failed.
+              |Coursera seems to be unavailable at the moment (Status $code)
+              |Check https://status.coursera.org/ and try again in a few minutes.
+           """.stripMargin
+        s.log.error(failedSubmitMsg)
+      }
+
+      // Failure, Coursera repsonds with an unexpected status code
+      else {
+        val failedSubmitMsg =
+          s"""|Submission failed.
+              |Coursera replied with an unexpected code (Status $code)
+           """.stripMargin
+        s.log.error(failedSubmitMsg)
+      }
+    }
+
+    // kick it all off, actually make request
+    postSubmission(json) match {
+      case Success(resp) => reportCourseraResponse(resp)
+      case Failure(e) =>
+        val failedConnectMsg =
+          s"""|Connection to Coursera failed.
+              |There was something wrong while attempting to connect to Coursera.
+              |Check your internet connection.
+              |${e.toString}""".stripMargin
+        s.log.error(failedConnectMsg)
+    }
+
+   }
+*/
+
+  def failSubmit(): Nothing = {
+    sys.error("Submission failed")
+  }
+
+  /**
+    * *****************
+    * DEALING WITH JARS
+    */
+  def encodeBase64(bytes: Array[Byte]): String =
+    new String(Base64.encodeBase64(bytes))
+}

project/build.properties

@@ -0,0 +1 @@
+sbt.version=1.2.8

project/buildSettings.sbt

@@ -0,0 +1,7 @@
+// Used for base64 encoding
+libraryDependencies += "commons-codec" % "commons-codec" % "1.10"
+
+// Used for Coursera submussion
+// libraryDependencies += "org.scalaj" %% "scalaj-http" % "2.3.0"
+// libraryDependencies += "com.typesafe.play" %% "play-json" % "2.6.9"
+

project/plugins.sbt

@@ -0,0 +1,2 @@
+addSbtPlugin("io.get-coursier" % "sbt-coursier" % "2.0.0-RC3-5")
+addSbtPlugin("ch.epfl.lamp" % "sbt-dotty" % "0.3.4")

src/main/scala/quickcheck/Heap.scala

@@ -0,0 +1,119 @@
+package quickcheck
+
+trait IntHeap extends Heap {
+  override type A = Int
+  override def ord = scala.math.Ordering.Int
+}
+
+// http://www.brics.dk/RS/96/37/BRICS-RS-96-37.pdf
+
+// Figure 1, page 3
+trait Heap {
+  type H // type of a heap
+  type A // type of an element
+  def ord: Ordering[A] // ordering on elements
+
+  def empty: H // the empty heap
+  def isEmpty(h: H): Boolean // whether the given heap h is empty
+
+  def insert(x: A, h: H): H // the heap resulting from inserting x into h
+  def meld(h1: H, h2: H): H // the heap resulting from merging h1 and h2
+
+  def findMin(h: H): A // a minimum of the heap h
+  def deleteMin(h: H): H // a heap resulting from deleting a minimum of h
+}
+
+// Figure 3, page 7
+trait BinomialHeap extends Heap {
+
+  type Rank = Int
+  case class Node(x: A, r: Rank, c: List[Node])
+  override type H = List[Node]
+
+  protected def root(t: Node) = t.x
+  protected def rank(t: Node) = t.r
+  protected def link(t1: Node, t2: Node): Node = // t1.r == t2.r
+    if ord.lteq(t1.x, t2.x) then
+      Node(t1.x, t1.r + 1, t2 :: t1.c)
+    else
+      Node(t2.x, t2.r + 1, t1 :: t2.c)
+  protected def ins(t: Node, ts: H): H = ts match
+    case Nil => List(t)
+    case tp :: ts => // t.r <= tp.r
+      if t.r < tp.r then
+        t :: tp :: ts
+      else
+        ins(link(t, tp), ts)
+
+  override def empty = Nil
+  override def isEmpty(ts: H) = ts.isEmpty
+
+  override def insert(x: A, ts: H) = ins(Node(x, 0, Nil), ts)
+  override def meld(ts1: H, ts2: H) = (ts1, ts2) match
+    case (Nil, ts) => ts
+    case (ts, Nil) => ts
+    case (t1 :: ts1, t2 :: ts2) =>
+      if t1.r < t2.r then
+        t1 :: meld(ts1, t2 :: ts2)
+      else if t2.r < t1.r then
+        t2 :: meld(t1 :: ts1, ts2)
+      else
+        ins(link(t1, t2), meld(ts1, ts2))
+
+  override def findMin(ts: H) = ts match
+    case Nil => throw new NoSuchElementException("min of empty heap")
+    case t :: Nil => root(t)
+    case t :: ts =>
+      val x = findMin(ts)
+      if ord.lteq(root(t), x) then
+        root(t)
+      else
+        x
+  override def deleteMin(ts: H) = ts match
+    case Nil => throw new NoSuchElementException("delete min of empty heap")
+    case t :: ts =>
+      def getMin(t: Node, ts: H): (Node, H) = ts match
+        case Nil => (t, Nil)
+        case tp :: tsp =>
+          val (tq, tsq) = getMin(tp, tsp)
+          if ord.lteq(root(t), root(tq)) then
+            (t, ts)
+          else
+            (tq, t :: tsq)
+      val (Node(_, _, c), tsq) = getMin(t, ts)
+      meld(c.reverse, tsq)
+}
+
+trait Bogus1BinomialHeap extends BinomialHeap {
+  override def findMin(ts: H) = ts match
+    case Nil => throw new NoSuchElementException("min of empty heap")
+    case t :: ts => root(t)
+}
+
+trait Bogus2BinomialHeap extends BinomialHeap {
+  override protected def link(t1: Node, t2: Node): Node = // t1.r == t2.r
+    if !ord.lteq(t1.x, t2.x) then
+      Node(t1.x, t1.r + 1, t2 :: t1.c)
+    else
+      Node(t2.x, t2.r + 1, t1 :: t2.c)
+}
+
+trait Bogus3BinomialHeap extends BinomialHeap {
+  override protected def link(t1: Node, t2: Node): Node = // t1.r == t2.r
+    if ord.lteq(t1.x, t2.x) then
+      Node(t1.x, t1.r + 1, t1 :: t1.c)
+    else
+      Node(t2.x, t2.r + 1, t2 :: t2.c)
+}
+
+trait Bogus4BinomialHeap extends BinomialHeap {
+  override def deleteMin(ts: H) = ts match
+    case Nil => throw new NoSuchElementException("delete min of empty heap")
+    case t :: ts => meld(t.c.reverse, ts)
+}
+
+trait Bogus5BinomialHeap extends BinomialHeap {
+  override def meld(ts1: H, ts2: H) = ts1 match
+    case Nil => ts2
+    case t1 :: ts1 => List(Node(t1.x, t1.r, ts1 ++ ts2))
+}

src/main/scala/quickcheck/QuickCheck.scala

@@ -0,0 +1,18 @@
+package quickcheck
+
+import org.scalacheck._
+import Arbitrary._
+import Gen._
+import Prop.{BooleanOperators => _, _}
+
+abstract class QuickCheckHeap extends Properties("Heap") with IntHeap {
+
+  lazy val genHeap: Gen[H] = ???
+  implicit lazy val arbHeap: Arbitrary[H] = Arbitrary(genHeap)
+
+  property("gen1") = forAll { (h: H) =>
+    val m = if isEmpty(h) then 0 else findMin(h)
+    findMin(insert(m, h)) == m
+  }
+
+}

src/test/scala/quickcheck/QuickCheckSuite.scala

@@ -0,0 +1,55 @@
+package quickcheck
+
+import org.scalacheck.Properties
+import org.junit._
+
+import org.scalacheck.Arbitrary._
+import org.scalacheck.Prop
+import org.scalacheck.Prop.{BooleanOperators => _, _}
+import org.scalacheck.Test.{check, Result, Failed, PropException}
+
+object QuickCheckBinomialHeap extends QuickCheckHeap with BinomialHeap
+
+class QuickCheckSuite {
+  def checkBogus(p: Properties): Unit =
+    def fail = throw new AssertionError(
+      s"A bogus heap should NOT satisfy all properties. Try to find the bug!")
+
+    check(asProp(p))(identity) match
+      case r: Result => r.status match
+        case _: Failed =>
+          () // OK: scalacheck found a counter example!
+        case p: PropException =>
+          p.e match
+            case e: NoSuchElementException =>
+              () // OK: the implementation throws NSEE
+            case _ =>
+              fail
+        case _ =>
+          fail
+
+  /** Turns a `Properties` instance into a single `Prop` by combining all the properties */
+  def asProp(properties: Properties): Prop = Prop.all(properties.properties.map(_._2).toSeq:_*)
+
+  @Test def `Binomial heap satisfies properties. (5pts)`: Unit =
+    Assert.assertTrue(
+      check(asProp(new QuickCheckHeap with quickcheck.test.BinomialHeap))(identity).passed
+    )
+
+  @Test def `Bogus (1) binomial heap does not satisfy properties. (10pts)`: Unit =
+    checkBogus(new QuickCheckHeap with quickcheck.test.Bogus1BinomialHeap)
+
+  @Test def `Bogus (2) binomial heap does not satisfy properties. (10pts)`: Unit =
+    checkBogus(new QuickCheckHeap with quickcheck.test.Bogus2BinomialHeap)
+
+  @Test def `Bogus (3) binomial heap does not satisfy properties. (10pts)`: Unit =
+    checkBogus(new QuickCheckHeap with quickcheck.test.Bogus3BinomialHeap)
+
+  @Test def `Bogus (4) binomial heap does not satisfy properties. (10pts)`: Unit =
+    checkBogus(new QuickCheckHeap with quickcheck.test.Bogus4BinomialHeap)
+
+  @Test def `Bogus (5) binomial heap does not satisfy properties. (10pts)`: Unit =
+    checkBogus(new QuickCheckHeap with quickcheck.test.Bogus5BinomialHeap)
+
+  @Rule def individualTestTimeout = new org.junit.rules.Timeout(10 * 1000)
+}

src/test/scala/quickcheck/test/Heap.scala

@@ -0,0 +1,96 @@
+package quickcheck.test
+
+// Figure 3, page 7
+trait BinomialHeap extends quickcheck.Heap {
+
+  type Rank = Int
+  case class Node(x: A, r: Rank, c: List[Node])
+  override type H = List[Node]
+
+  protected def root(t: Node) = t.x
+  protected def rank(t: Node) = t.r
+  protected def link(t1: Node, t2: Node): Node = // t1.r == t2.r
+    if ord.lteq(t1.x, t2.x) then
+      Node(t1.x, t1.r + 1, t2 :: t1.c)
+    else
+      Node(t2.x, t2.r + 1, t1 :: t2.c)
+  protected def ins(t: Node, ts: H): H = ts match
+    case Nil => List(t)
+    case tp :: ts => // t.r<=tp.r
+      if t.r < tp.r then
+        t :: tp :: ts
+      else
+        ins(link(t, tp), ts)
+
+  override def empty = Nil
+  override def isEmpty(ts: H) = ts.isEmpty
+
+  override def insert(x: A, ts: H) = ins(Node(x, 0, Nil), ts)
+  override def meld(ts1: H, ts2: H) = (ts1, ts2) match
+    case (Nil, ts) => ts
+    case (ts, Nil) => ts
+    case (t1 :: ts1, t2 :: ts2) =>
+      if t1.r < t2.r then
+        t1 :: meld(ts1, t2 :: ts2)
+      else if t2.r < t1.r then
+        t2 :: meld(t1 :: ts1, ts2)
+      else
+        ins(link(t1, t2), meld(ts1, ts2))
+
+  override def findMin(ts: H) = ts match
+    case Nil => throw new NoSuchElementException("min of empty heap")
+    case t :: Nil => root(t)
+    case t :: ts =>
+      val x = findMin(ts)
+      if ord.lteq(root(t), x) then
+        root(t)
+      else
+        x
+  override def deleteMin(ts: H) = ts match
+    case Nil => throw new NoSuchElementException("delete min of empty heap")
+    case t :: ts =>
+      def getMin(t: Node, ts: H): (Node, H) = ts match
+        case Nil => (t, Nil)
+        case tp :: tsp =>
+          val (tq, tsq) = getMin(tp, tsp)
+          if ord.lteq(root(t), root(tq)) then
+            (t, ts)
+          else
+            (tq, t :: tsq)
+      val (Node(_, _, c), tsq) = getMin(t, ts)
+      meld(c.reverse, tsq)
+}
+
+trait Bogus1BinomialHeap extends BinomialHeap {
+  override def findMin(ts: H) = ts match
+    case Nil => throw new NoSuchElementException("min of empty heap")
+    case t :: ts => root(t)
+}
+
+trait Bogus2BinomialHeap extends BinomialHeap {
+  override protected def link(t1: Node, t2: Node): Node = // t1.r == t2.r
+    if !ord.lteq(t1.x, t2.x) then
+      Node(t1.x, t1.r + 1, t2 :: t1.c)
+    else
+      Node(t2.x, t2.r + 1, t1 :: t2.c)
+}
+
+trait Bogus3BinomialHeap extends BinomialHeap {
+  override protected def link(t1: Node, t2: Node): Node = // t1.r == t2.r
+    if ord.lteq(t1.x, t2.x) then
+      Node(t1.x, t1.r + 1, t1 :: t1.c)
+    else
+      Node(t2.x, t2.r + 1, t2 :: t2.c)
+}
+
+trait Bogus4BinomialHeap extends BinomialHeap {
+  override def deleteMin(ts: H) = ts match
+    case Nil => throw new NoSuchElementException("delete min of empty heap")
+    case t :: ts => meld(t.c.reverse, ts)
+}
+
+trait Bogus5BinomialHeap extends BinomialHeap {
+  override def meld(ts1: H, ts2: H) = ts1 match
+    case Nil => ts2
+    case t1 :: ts1 => List(Node(t1.x, t1.r, ts1++ts2))
+}

student.sbt

@@ -0,0 +1,9 @@
+// Used for base64 encoding
+libraryDependencies += "commons-codec" % "commons-codec" % "1.10"
+
+// Used for Coursera submussion
+// libraryDependencies += "org.scalaj" %% "scalaj-http" % "2.4.2"
+// libraryDependencies += "com.typesafe.play" %% "play-json" % "2.7.4"
+
+// Student tasks (i.e. packageSubmission)
+enablePlugins(StudentTasks)