Problem 15 updated

pavelfatin · ff3e612a25420bd25cbb43025c455a8ce9e41625 · pavelfatin committed Dec 8, 2013 · Dec 8, 2013 · ff3e612
1 parent 580368c
commit ff3e612a25420bd25cbb43025c455a8ce9e41625
Unified Split

Showing with 3 additions and 6 deletions.

+3 −6 p15.scala
diff --git a/p15.scala b/p15.scala
@@ -1,9 +1,6 @@
-def f(row: Seq[Long], c: Int): Long = {
-  var s = 0L
-  val next = row.map { n => s += n; s }
-  if(c == 0) next.last else f(next, c - 1)
-}
+def f(row: Seq[Long], c: Int): Long =
+  if (c == 0) row.last else f(row.scan(0L)(_ + _), c - 1)
 
-def r(n: Int) = f(List.fill(n + 1)(1L), n - 1)
+def r(n: Int) = f(Seq.fill(n + 1)(1L), n)
 
 assert(r(20) == 137846528820L) // 1 ms