Data commit

Task/Binary-search/Scala/binary-search-1.scala

@@ -0,0 +1,9 @@
+def binarySearch[A <% Ordered[A]](a: IndexedSeq[A], v: A) = {
+  def recurse(low: Int, high: Int): Option[Int] = (low + high) / 2 match {
+    case _ if high < low => None
+    case mid if a(mid) > v => recurse(low, mid - 1)
+    case mid if a(mid) < v => recurse(mid + 1, high)
+    case mid => Some(mid)
+  }
+  recurse(0, a.size - 1)
+}

Task/Binary-search/Scala/binary-search-2.scala

@@ -0,0 +1,12 @@
+def binarySearch[T](xs: Seq[T], x: T)(implicit ordering: Ordering[T]): Option[Int] = {
+    var low: Int = 0
+    var high: Int = xs.size - 1
+
+    while (low <= high)
+      low + high >>> 1 match {
+        case guess if ordering.gt(xs(guess), x) => high = guess - 1 //too high
+        case guess if ordering.lt(xs(guess), x) => low = guess + 1 // too low
+        case guess => return Some(guess) //found it
+      }
+    None //not found
+  }

Task/Binary-search/Scala/binary-search-3.scala

@@ -0,0 +1,10 @@
+def testBinarySearch(n: Int) = {
+  val odds = 1 to n by 2
+  val result = (0 to n).flatMap(binarySearch(odds, _))
+  assert(result == (0 until odds.size))
+  println(s"$odds are odd natural numbers")
+  for (it <- result)
+    println(s"$it is ordinal of ${odds(it)}")
+}
+
+def main() = testBinarySearch(12)