A-M baby

Task/Greatest-subsequential-sum/Scala/greatest-subsequential-sum.scala

@@ -0,0 +1,25 @@
+def maxSubseq(l: List[Int]) = l.scanRight(Nil : List[Int]) {
+  case (el, acc) if acc.sum + el < 0 => Nil
+  case (el, acc)                     => el :: acc
+} max Ordering.by((_: List[Int]).sum)
+
+def biggestMaxSubseq(l: List[Int]) = l.scanRight(Nil : List[Int]) {
+  case (el, acc) if acc.sum + el < 0 => Nil
+  case (el, acc)                     => el :: acc
+} max Ordering.by((ss: List[Int]) => (ss.sum, ss.length))
+
+def biggestMaxSubseq[N](l: List[N])(implicit n: Numeric[N]) = {
+  import n._
+  l.scanRight(Nil : List[N]) {
+    case (el, acc) if acc.sum + el < zero => Nil
+    case (el, acc)                        => el :: acc
+  } max Ordering.by((ss: List[N]) => (ss.sum, ss.length))
+}
+
+def linearBiggestMaxSubseq[N](l: List[N])(implicit n: Numeric[N]) = {
+  import n._
+  l.scanRight((zero, Nil : List[N])) {
+    case (el, (acc, _)) if acc + el < zero => (zero, Nil)
+    case (el, (acc, ss))                   => (acc + el, el :: ss)
+  } max Ordering.by((t: (N, List[N])) => (t._1, t._2.length)) _2
+}