Merge pull request #54 from andreas-roehler/master

solution2.1.7.10 fixes

chapter02/worksheets/solution2.1.7.10_IntelliJ.scala

@@ -0,0 +1,39 @@
+/** author: Andreas Röhler */
+
+/** 
+  Exercise 2.1.7.10
+  Given a Seq[List[Int]], compute a new Seq[List[Int]] where each list contains three largest elements from the initial list (or fewer than three if the initial list is
+  shorter). So, for the input:
+
+  Seq(List(0, 50, 5, 10, 30), List(100), List(1, 2, 200, 20))
+
+  the output must be:
+
+  Seq(List(50, 30, 10), List(100), List(200, 20, 2))
+  
+Hint: use map, sortBy, take.
+ */
+
+object LargestTree {
+  def largestTree(a: Seq[List[Int]]): Seq[List[Int]] = {
+    val x = a.map{ k=>k.sortBy(k=>(-k))}.map{ k => k.take(3) }
+    printf("largestTree %s:\n", x)
+    x
+  }
+  def main(args: Array[String]) = {
+    val expected = Seq(List(50, 30, 10), List(100), List(200, 20, 2))
+    val result =  this.largestTree(Seq(List(50, 30, 10), List(100), List(200, 20, 2)))
+    assert(result == expected)
+    if (result == expected) println("solution2.1.7.10_object_main result: %s\n".format(result))
+  }
+  LargestTree.main(Array())
+}
+
+// IntelliJ:
+
+// /usr/lib/jvm/java-1.11.0-openjdk-amd64/bin/java -javaagent:/snap/intellij-idea-community/491/lib/idea_rt.jar=38493:/snap/intellij-idea-community/491/bin -Dfile.encoding=UTF-8 -classpath /home/speck/IdeaProjects/aktuell/out/production/aktuell:/usr/share/scala-2.11/lib/scala-library.jar:/usr/share/scala-2.11/lib/scala-actors.jar:/usr/share/scala-2.11/lib/scala-reflect.jar:/usr/share/scala-2.11/lib/scala-parser-combinators.jar:/usr/share/scala-2.11/lib/scala-xml.jar LargestTree
+// largestTree List(List(50, 30, 10), List(100), List(200, 20, 2)):
+// solution2.1.7.10_object_main result: List(List(50, 30, 10), List(100), List(200, 20, 2))
+
+// largestTree List(List(50, 30, 10), List(100), List(200, 20, 2)):
+// solution2.1.7.10_object_main result: List(List(50, 30, 10), List(100), List(200, 20, 2))

chapter02/worksheets/solution2.1.7.10_w_print.scala

@@ -20,25 +20,17 @@ object LargestTree {
     printf("largestTree %s:\n", x)
     x
   }
-  def main(args: Array[String]) {
+  def main(args: Array[String]) = {
     val expected = Seq(List(50, 30, 10), List(100), List(200, 20, 2))
     val result =  this.largestTree(Seq(List(50, 30, 10), List(100), List(200, 20, 2)))
     assert(result == expected)
     if (result == expected) println("solution2.1.7.10_object_main result: %s\n".format(result))
-
   }
 }
 
 LargestTree.main(Array())
 
-// scala> LargestTree.largestTree(Seq(List(50, 30, 10, 90), List(100), List(200, 20, 2, 66)))
-// largestTree List(List(90, 50, 30), List(100), List(200, 66, 20)):
-// res7: Seq[List[Int]] = List(List(90, 50, 30), List(100), List(200, 66, 20))
-
-// s$ scala solution2.1.7.10_w_print.scala
-// ...solution2.1.7.10_w_print.scala:32: warning: Script has a main object but statement is disallowed
-// LargestTree.main(Array())
-//                 ^
-// one warning found
+// scala> :load solution2.1.7.10_w_print.scala
+// :load solution2.1.7.10_w_print.scala
 // largestTree List(List(50, 30, 10), List(100), List(200, 20, 2)):
 // solution2.1.7.10_object_main result: List(List(50, 30, 10), List(100), List(200, 20, 2))