Merge pull request #8 from mariotti/javascalawork

Javascalawork

Author: mariotti

java_questions/Q3_isRotated.java

@@ -0,0 +1,18 @@
+#From: http://stackoverflow.com/questions/2553522/interview-question-check-if-one-string-is-a-rotation-of-other-string
+# Answer from: comunity wiki
+# a litteral copy
+# Just a java started
+#
+#algorithm checkRotation(string s1, string s2) 
+#  if( len(s1) != len(s2))
+#    return false
+#  if( substring(s2,concat(s1,s1))
+#    return true
+#  return false
+#end
+#
+
+boolean isRotation(String s1,String s2) {
+    return (s1.length() == s2.length()) && ((s1+s1).indexOf(s2) != -1);
+}
+

scala_questions/Q1_MostFrequentInt.scala

@@ -0,0 +1,32 @@
+/*
+# This is almost a copy paste from:
+# http://stackoverflow.com/questions/13878104/finding-the-most-frequent-common-element-in-a-collection
+# which is in principle under the MIT licence, See for example the discussion here:
+# https://meta.stackexchange.com/questions/271080/the-mit-license-clarity-on-using-code-on-stack-overflow-and-stack-exchange
+#
+*/
+object MostFrequentInt extends App {
+val lista = List(0, 1, 3, 2, 23, 43, 2, 1, 5, 2, 5, 2, 56, 23, 0, -1, 2, 2)
+val listb = List(4, 0, 1, 0, 4, 4, 4, 4, 0, 1, 1, 1,-6, 7)
+val listc = List(3, 5, 10, 3, 5, 1, 5, 3, 2, 3, 8, 4, 5, 1, 2, 7, 4, 6, 5, 8, 1, 1, 7, 10, 4, 5, 10, 5, 9, 1, 2, 10, 3, 9, 5, 10, 6, 10, 10, 8, 7, 2, 10, 7, 8, 10, 10, 7, 5, 10)
+  println("Start")
+  println(lista.groupBy(identity).maxBy(_._2.size)._1)
+  println(listb.groupBy(identity).maxBy(_._2.size)._1)
+  println(listc.groupBy(identity).maxBy(_._2.size)._1)
+}
+
+/*
+As I am new to scala, to understand the code above... if you know python and/or java and/or perl...
+groupBy returns a Map (hashkey, dictionary, or similar) like:
+
+scala> lista.groupBy(identity)
+res3: scala.collection.immutable.Map[Int,List[Int]] = Map(0 -> List(0, 0), 5 -> List(5, 5), 56 -> List(56), 1 -> List(1, 1), 2 -> List(2, 2, 2, 2, 2, 2), 3 -> List(3), -1 -> List(-1), 43 -> List(43), 23 -> List(23, 23))
+
+MaxBy argument means: _ get the coming objects (the Map),
+                      _._2 use the second argument (the List),
+		      _._2.size of it consider the size and find the max.
+
+
+The REPL seems to be one of the nice things of scala ;)
+
+*/

scala_questions/Q2_PairsEqualToTen.scala

@@ -0,0 +1,52 @@
+/*
+Adapted from the tutorial at:
+http://docs.scala-lang.org/tutorials/tour/sequence-comprehensions.html
+*/
+
+object PairsEqualToTen extends App {
+  val lista = List(0, 1, 3, 2, 23, 43, 2, 1, 5, 2, 5, 2, 56, 23, 0, -1, 2, 2)
+  val listb = List(4, 0, 1, 0, 4, 4, 4, 4, 0, 1, 1, 1,-6, 7)
+  val listc = List(3, 5, 10, 3, 5, 1, 5, 3, 2, 3, 8, 4, 5, 1, 2, 7, 4, 6, 5, 8, 1, 1, 7, 10, 4, 5, 10, 5, 9, 1, 2, 10, 3, 9, 5, 10, 6, 10, 10, 8, 7, 2, 10, 7, 8, 10, 10, 7, 5, 10)
+  val listd = List(0, 1, 3, 2, 7, 43, 2, 1, 5, 2, 5, 2, 8, 23, 0, -1, 2, 2)
+  val liste = List(0, 1, 3, 10, 9, 7, 5, 5)
+
+def foo(lst: List[Int], v: Int) =
+    for ((i, idx) <- lst.view.zipWithIndex;
+         j <- lst.slice(idx+1, lst.size) if i + j == v) yield{
+      //Console.println(i, j, idx, lst.slice(idx+1, lst.size))
+      (i, j)
+      }
+      
+  Console.println(lista)      
+  foo(lista, 10) foreach {
+    case (i, j) =>
+      println(s"($i, $j)")
+  }
+
+  Console.println(listb)      
+  foo(listb, 10) foreach {
+    case (i, j) =>
+      println(s"($i, $j)")
+  }
+
+  Console.println(listc)      
+  foo(listc, 10) foreach {
+    case (i, j) =>
+      println(s"($i, $j)")
+  }
+
+  Console.println(listd)      
+  foo(listd, 10) foreach {
+    case (i, j) =>
+      println(s"($i, $j)")
+  }
+
+  Console.println(liste)      
+  foo(liste, 10) foreach {
+    case (i, j) =>
+      println(s"($i, $j)")
+  }
+
+
+}
+