adding Project Euler problems in the folder Project Euler

src/main/scala/ProjectEuler/Euler1.scala

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+package ProjectEuler
+
+object Euler1 {
+    /** 
+	*Problem Statement : If we list all the natural numbers
+	* below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9.
+	*The sum of these multiples is 23.
+
+	*Find the sum of all the multiples of 3 or 5 below 1000.
+
+    **/
+
+    def main (args : Array[String]) {
+        val sum = (1 until 1000).filter(n => n % 3 == 0 || n % 5 == 0).sum
+        println(sum)
+    }   
+}
+

src/main/scala/ProjectEuler/Euler2.scala

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+package ProjectEuler
+
+object Euler2 {
+    /** 
+	*Problem Statement : Each new term in the Fibonacci sequence
+	*is generated by adding the previous two terms. 
+	*By starting with 1 and 2, the first 10 terms will be:
+
+	*1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...
+
+	*By considering the terms in the Fibonacci sequence whose 		*values do not exceed four million,
+	*find the sum of the even-valued terms.
+
+    **/
+
+    def nextFib(x: Int, y: Int): Stream[Int] = { 
+        x #:: nextFib(y, x+y)
+    }
+
+    def fib = nextFib(1,1)
+
+    def main (args : Array[String]) {
+        println(fib.takeWhile(_ <= 4000000).filter(_ % 2 == 0).sum)
+    }
+
+}
+

src/main/scala/ProjectEuler/Euler3.scala

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+package ProjectEuler
+
+object Euler3 {
+    /** 
+	*Problem Statement : The prime factors of 13195 are 5, 7, 13 and 29.
+
+	*What is the largest prime factor of the number 600851475143 ?
+
+    **/
+
+	def primeFactors(num: Long): List[Long] = {
+            val exists = (2L to math.sqrt(num).toLong).find(num % _ == 0)
+            exists match {
+		case None => List(num)
+                case Some(d) => d :: primeFactors(num/d)
+            }
+    	}
+
+	def main(args : Array[String]) {
+	    println(primeFactors(600851475143L).last)
+        }
+}

src/main/scala/ProjectEuler/Euler4.scala

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+package ProjectEuler
+
+object Euler4 {
+    /** 
+	*Problem Statement : A palindromic number reads the same both ways.
+	*The largest palindrome made from the product of two 2-digit numbers is 9009 = 91 × 99.
+
+	*Find the largest palindrome made from the product of two 3-digit numbers.
+
+    **/
+	def isPalindrome(num: Int): Boolean = {
+	    val numString = num.toString
+	    numString == numString.reverse
+	}
+
+	def main(args : Array[String]){
+	    val palindromes = for (x <- 100 to 999; y <- 100 to 999 if (isPalindrome(x * y))) yield x*y
+	    println(palindromes.max)
+	}
+}
+