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SergiiVlasiuk's solution

to Sublist in the Scala Track

Published at Aug 26 2019 · 0 comments
Instructions
Test suite
Solution

Given two lists determine if the first list is contained within the second list, if the second list is contained within the first list, if both lists are contained within each other or if none of these are true.

Specifically, a list A is a sublist of list B if by dropping 0 or more elements from the front of B and 0 or more elements from the back of B you get a list that's completely equal to A.

Examples:

  • A = [1, 2, 3], B = [1, 2, 3, 4, 5], A is a sublist of B
  • A = [3, 4, 5], B = [1, 2, 3, 4, 5], A is a sublist of B
  • A = [3, 4], B = [1, 2, 3, 4, 5], A is a sublist of B
  • A = [1, 2, 3], B = [1, 2, 3], A is equal to B
  • A = [1, 2, 3, 4, 5], B = [2, 3, 4], A is a superlist of B
  • A = [1, 2, 4], B = [1, 2, 3, 4, 5], A is not a superlist of, sublist of or equal to B

The Scala exercises assume an SBT project scheme. The exercise solution source should be placed within the exercise directory/src/main/scala. The exercise unit tests can be found within the exercise directory/src/test/scala.

To run the tests simply run the command sbt test in the exercise directory.

For more detailed info about the Scala track see the help page.

Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

SublistTest.scala

import org.scalatest.{Matchers, FunSuite}

/** @version 1.1.0 */
class SublistTest extends FunSuite with Matchers {

  test("empty lists") {
    Sublist.sublist(List(), List()) should be(Sublist.Equal)
  }

  test("empty list within non empty list") {
    pending
    Sublist.sublist(List(), List(1, 2, 3)) should be(Sublist.Sublist)
  }

  test("non empty list contains empty list") {
    pending
    Sublist.sublist(List(1, 2, 3), List()) should be(Sublist.Superlist)
  }

  test("list equals itself") {
    pending
    Sublist.sublist(List(1, 2, 3), List(1, 2, 3)) should be(Sublist.Equal)
  }

  test("different lists") {
    pending
    Sublist.sublist(List(1, 2, 3), List(2, 3, 4)) should be(Sublist.Unequal)
  }

  test("false start") {
    pending
    Sublist.sublist(List(1, 2, 5), List(0, 1, 2, 3, 1, 2, 5, 6)) should be(
      Sublist.Sublist)
  }

  test("consecutive") {
    pending
    Sublist.sublist(List(1, 1, 2), List(0, 1, 1, 1, 2, 1, 2)) should be(
      Sublist.Sublist)
  }

  test("sublist at start") {
    pending
    Sublist.sublist(List(0, 1, 2), List(0, 1, 2, 3, 4, 5)) should be(
      Sublist.Sublist)
  }

  test("sublist in middle") {
    pending
    Sublist.sublist(List(2, 3, 4), List(0, 1, 2, 3, 4, 5)) should be(
      Sublist.Sublist)
  }

  test("sublist at end") {
    pending
    Sublist.sublist(List(3, 4, 5), List(0, 1, 2, 3, 4, 5)) should be(
      Sublist.Sublist)
  }

  test("at start of superlist") {
    pending
    Sublist.sublist(List(0, 1, 2, 3, 4, 5), List(0, 1, 2)) should be(
      Sublist.Superlist)
  }

  test("in middle of superlist") {
    pending
    Sublist.sublist(List(0, 1, 2, 3, 4, 5), List(2, 3)) should be(
      Sublist.Superlist)
  }

  test("at end of superlist") {
    pending
    Sublist.sublist(List(0, 1, 2, 3, 4, 5), List(3, 4, 5)) should be(
      Sublist.Superlist)
  }

  test("first list missing element from second list") {
    pending
    Sublist.sublist(List(1, 3), List(1, 2, 3)) should be(Sublist.Unequal)
  }

  test("second list missing element from first list") {
    pending
    Sublist.sublist(List(1, 2, 3), List(1, 3)) should be(Sublist.Unequal)
  }

  test("order matters to a list") {
    pending
    Sublist.sublist(List(1, 2, 3), List(3, 2, 1)) should be(Sublist.Unequal)
  }

  test("same digits but different numbers") {
    pending
    Sublist.sublist(List(1, 0, 1), List(10, 1)) should be(Sublist.Unequal)
  }
}
object Sublist extends Enumeration {
  val Equal, Sublist, Superlist, Unequal = Value

  def sublist[A](xs: List[A], ys: List[A]) = {
    if (xs == ys) Equal
    else if (xs containsSlice ys) Superlist
    else if (ys containsSlice xs) Sublist
    else Unequal
  }
}

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