BruteForce

scala/src/main/scala/ch32_matching/BruteForce.scala

@@ -0,0 +1,24 @@
+package ch32_matching
+
+import scala.util.control.Breaks._
+
+object BruteForce {
+
+  def firstIndexOf(main: Array[Char], sub: Array[Char]): Int = {
+
+    require(main != null, "main array required")
+    require(sub != null, "sub array required")
+    require(main.length >= sub.length, "sub array should be small than main array")
+    var result = -1
+    breakable {
+      for (i <- 0 until (main.length - sub.length)) {
+        if (main.slice(i, i + sub.length) sameElements sub) {
+          result = i
+          break
+        }
+      }
+    }
+    result
+  }
+
+}

scala/src/test/scala/ch32_matching/BruteForceTest.scala

@@ -0,0 +1,20 @@
+package ch32_matching
+
+import org.scalatest.{FlatSpec, Matchers}
+
+import scala.util.Random
+
+class BruteForceTest extends FlatSpec with Matchers {
+
+  behavior of "BruteForceTest"
+
+  it should "find firstIndexOf a sub string" in {
+    val random = Random.alphanumeric
+    val main = random.take(1000).toArray
+    val index = Random.nextInt(950)
+    val sub = random.take(1000).toArray.slice(index, index + 50)
+
+    BruteForce.firstIndexOf(main, sub) should equal(index)
+  }
+
+}