Puzzle 4.

Author: pauldoo

src/com/pauldoo/euler/puzzle/Puzzle4.scala

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+package com.pauldoo.euler.puzzle
+
+object Puzzle4 extends Puzzle {
+  def isPalindrome(s: String): Boolean = {
+    s.reverse.mkString == s;
+  }
+
+  def answer() = {
+    val allPalindromes = for (
+      i <- 100 to 999;
+      j <- 100 to 999;
+      val p = i * j if isPalindrome(p.toString())
+    ) yield p;
+    allPalindromes.sortWith(_ > _).head;
+  }
+}

test/com/pauldoo/euler/puzzle/Puzzle4Test.scala

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+package com.pauldoo.euler.puzzle
+import org.scalatest.FunSuite
+import org.junit.runner.RunWith
+import org.scalatest.junit.JUnitRunner
+
+@RunWith(classOf[JUnitRunner])
+class Puzzle4Test extends PuzzleTest {
+  def puzzle = Puzzle4;
+  def expectedAnswer = 906609;
+}