Added Scala Codebox

Author: mukel

HackerRank/ProjectEuler/Utils.scala

@@ -0,0 +1,59 @@
+object Utils {
+
+	val in = {
+		val lines = scala.io.Source.stdin.getLines
+		lines flatMap (_ split ' ' filter (_.nonEmpty))
+	}
+
+	def nextInt = in.next.toInt
+
+	val fibs: Stream[Long] = 1L #:: fibs.scanLeft(2L)(_ + _)
+
+	val primes: Stream[Int] = 2 #:: (Stream.from(3, 2) filter (n => primes.view takeWhile (p => p*p <= n) forall (n % _ != 0)))
+
+	@annotation.tailrec
+	def gcd(a: Int, b: Int): Int = if (b == 0) a else gcd(b, a % b)
+
+	def lcm(a: Int, b: Int): Int = a / gcd(a, b) * b
+
+	@annotation.tailrec
+	def binarySearch[T, U](key: U, xs: IndexedSeq[T], from: Int, end: Int, keyExtract: (T) => U = (x:T) => x)(implicit ordering: Ordering[U]): Option[Int] = {
+		if (from >= end) None
+		else {
+			val mid = (from + end) / 2
+			val t = keyExtract(xs(mid))
+			val cmp = ordering.compare(key, t)
+			if (cmp < 0) binarySearch(key, xs, from, mid, keyExtract)
+			else if (cmp > 0) binarySearch(key, xs, mid + 1, end, keyExtract)
+			else Some(mid)
+		}
+	}
+
+	def lowerBound[T, U](key: U, iseq: IndexedSeq[T], from: Int, end: Int, keyExtract: (T) => U = (x:T) => x)(implicit ordering: Ordering[U]): Int = {
+		var lo = from
+		var hi = end - 1
+		while (lo <= hi) {
+			val mid = (lo + hi) / 2
+			if (ordering.lteq(key, keyExtract(iseq(mid))))
+				hi = mid - 1
+			else
+				lo = mid + 1
+		}
+		hi + 1
+	}
+
+	def upperBound[T, U](key: U, iseq: IndexedSeq[T], from: Int, end: Int, keyExtract: (T) => U = (x:T) => x)(implicit ordering: Ordering[U]): Int = {
+		var lo = from
+		var hi = end - 1
+		while (lo <= hi) {
+			val mid = (lo + hi) / 2
+			if (ordering.lt(key, keyExtract(iseq(mid))))
+				hi = mid - 1
+			else
+				lo = mid + 1
+		}
+		hi + 1
+	}
+
+}
+