Scala : add 13-polynomials to sandbox

2 files changed, 44 insertions, 0 deletions

diff --git a/Scala/sandbox/0-main.scala b/Scala/sandbox/0-main.scala
index f6d6652..297fab9 100644
--- a/Scala/sandbox/0-main.scala
+++ b/Scala/sandbox/0-main.scala
@@ -15,5 +15,6 @@ object Main  extends App {
     MergeSort.run
     Pack.run
     NQueens.run
+    Polynomials.run
 
 }
diff --git a/Scala/sandbox/13-polynomials.scala b/Scala/sandbox/13-polynomials.scala
new file mode 100644
index 0000000..ebf3818
--- /dev/null
+++ b/Scala/sandbox/13-polynomials.scala
@@ -0,0 +1,43 @@
+object Polynomials
+{
+
+  class Poly(terms0: Map[Int, Double]) {
+    def this(bindings: (Int, Double)*) = this(bindings.toMap)
+    val terms = terms0 withDefaultValue 0.0
+
+    def add (other: Poly) = new Poly(terms ++ (other.terms map adjust))
+
+    def adjust(term: (Int, Double)): (Int, Double) = {
+      val (exp, coeff) = term
+      exp -> (coeff + terms(exp))
+      // before adding defauld value
+      /* terms get exp match { */
+      /*   case Some(coeff1) => exp -> (coeff + coeff1) */
+      /*   case None => exp -> coeff */
+      /* } */
+    }
+
+    def + (other: Poly) = new Poly((other.terms foldLeft terms)(addTerm))
+
+    def addTerm(terms: Map[Int, Double], term: (Int, Double)) = {
+      val (exp, coeff) = term
+      terms + (exp -> (coeff + terms(exp)))
+    }
+
+    override def toString =
+      (for ((exp, coeff) <- terms.toList.sorted.reverse) yield coeff+"^"+exp) mkString " + "
+  }
+
+  def run = {
+    println("Polynomials")
+    /* val p1 = new Poly(Map(1 -> 2.0, 3 -> 4.0, 5 -> 6.2)) */
+    /* val p2 = new Poly(Map(0 -> 3.0, 3 -> 7.0)) */
+    val p1 = new Poly(1 -> 2.0, 3 -> 4.0, 5 -> 6.2)
+    val p2 = new Poly(0 -> 3.0, 3 -> 7.0)
+    println(p1.terms(7))
+    println(p1)
+    println(p2)
+    println(p1 add p2)
+    println(p1 + p2)
+  }
+}