Scala : complete example

2 files changed, 53 insertions, 8 deletions

diff --git a/Scala/example/src/main/scala/example/Lists.scala b/Scala/example/src/main/scala/example/Lists.scala
index 4e5feee..628486c 100644
--- a/Scala/example/src/main/scala/example/Lists.scala
+++ b/Scala/example/src/main/scala/example/Lists.scala
@@ -23,7 +23,11 @@ object Lists {
    * @param xs A list of natural numbers
    * @return The sum of all elements in `xs`
    */
-  def sum(xs: List[Int]): Int = ???
+  def sum(xs: List[Int]): Int = {
+    def sumIter(acc: Int, xs: List[Int]): Int =
+      if (xs.isEmpty) acc else sumIter(acc + xs.head, xs.tail)
+    sumIter(0, xs)
+  }
 
   /**
    * This method returns the largest element in a list of integers. If the
@@ -38,5 +42,12 @@ object Lists {
    * @return The largest element in `xs`
    * @throws java.util.NoSuchElementException if `xs` is an empty list
    */
-  def max(xs: List[Int]): Int = ???
+  def max(xs: List[Int]): Int = {
+    def maxInt(a: Int, b: Int) = if (a>b) a else b
+    def maxIter(max: Int, xs: List[Int]): Int =
+      if (xs.isEmpty) max else maxIter(maxInt(max,xs.head), xs.tail)
+    if (xs.isEmpty) throw new NoSuchElementException
+    else maxIter(Integer.MIN_VALUE, xs)
+  }
+
 }
diff --git a/Scala/example/src/test/scala/example/ListsSuite.scala b/Scala/example/src/test/scala/example/ListsSuite.scala
index 4a52667..5973369 100644
--- a/Scala/example/src/test/scala/example/ListsSuite.scala
+++ b/Scala/example/src/test/scala/example/ListsSuite.scala
@@ -19,7 +19,7 @@ import org.scalatest.junit.JUnitRunner
  * inside eclipse using the built-in JUnit test runner.
  *
  * You have two options for running this test suite:
- * 
+ *
  * - Start the sbt console and run the "test" command
  * - Right-click this file in eclipse and chose "Run As" - "JUnit Test"
  */
@@ -47,7 +47,7 @@ class ListsSuite extends FunSuite {
    * This allows tests to be written in a more readable manner:
    */
   test("one plus one is three?") {
-    assert(1 + 1 == 3) // This assertion fails! Go ahead and fix it.
+    assert(1 + 1 == 2) // This assertion fails! Go ahead and fix it.
   }
 
 
@@ -72,7 +72,7 @@ class ListsSuite extends FunSuite {
    * We recommend to always use the `===` equality operator when writing tests.
    */
   test("details why one plus one is not three") {
-    assert(1 + 1 === 3) // Fix me, please!
+    assert(1 + 1 === 2) // Fix me, please!
   }
 
 
@@ -99,9 +99,9 @@ class ListsSuite extends FunSuite {
    * Now we finally write some tests for the list functions that have to be
    * implemented for this assignment. We fist import all members of the
    * `List` object.
-   */ 
+   */
   import Lists._
-  
+
 
   /**
    * We only provide two very basic tests for you. Write more tests to make
@@ -114,11 +114,45 @@ class ListsSuite extends FunSuite {
    * however it is recommended to write an individual `test` statement for
    * every tested aspect of a method.
    */
+  test("sum of a 1 number list") {
+    assert(sum(List(666)) === 666)
+  }
+
   test("sum of a few numbers") {
     assert(sum(List(1,2,0)) === 3)
   }
-  
+
+  test("sum of an empty list") {
+    assert(sum(List()) === 0)
+  }
+
+  test("sum of a same numbers") {
+    assert(sum(List(2,2,2,2,2)) === 10)
+  }
+
+  test("sum of a few positives and negatives numbers") {
+    assert(sum(List(1,2,0,-3,-8)) === -8)
+  }
+
+  test("max of a 1 number list") {
+    assert(max(List(666)) === 666)
+  }
+
+  test("max of an empty list throws NoSuchElementException") {
+    intercept[NoSuchElementException] {
+      max(List())
+    }
+  }
+
   test("max of a few numbers") {
     assert(max(List(3, 7, 2)) === 7)
   }
+
+  test("max of negatives numbers") {
+    assert(max(List(-3, -7, -2, -5)) === -2)
+  }
+
+  test("max of a few positives and negatives numbers") {
+    assert(max(List(3, 7, 0, -5)) === 7)
+  }
 }