title: Tail Recursion
signature: def tailRecursion(n: Int) = {
test_code: import scala.collection.mutable.HashMap
  import scala.collection.immutable.HashSet
  
  
  // SOLUTION CODE
  // ============================================
  PLACEHOLDER_CODE_BODY
  
  
  // TESTING CODE 
  // ============================================
  def validateSolution(actual: Long , expected: Long): Boolean = {
      actual.toString == expected.toString
  }
  
  def driver(n: Int, expected: Long): String = {
      try {
          if (validateSolution(PLACEHOLDER_FN_NAME(n),expected)) {
              "PASSED"
          } else{
              "FAILED"
          }
      }catch{
          case e: Exception => {e.getClass.getName}
      }
  
  }
  object QuestionEvaluator extends App {
  
      println(s"TEST-0...${driver(
        16, 
        20922789888000L    
      )}")   
  
  }
  
source_py: def tail_recursion(n):
      if (n == 0):
          return 1
      return (n * tail_recursion((n - 1)))
source_cpp: unsigned int tail_recursion(unsigned int n) {
    if ( n == 0 ) return 1;
    return n * tail_recursion ( n - 1 );
  }