title: Binary Search
signature: def binarySearch(arr: List[Int], l: Int, r: Int, x: Int) = {
test_code: import scala.collection.mutable.HashMap
  import scala.collection.immutable.HashSet
  
  
  // SOLUTION CODE
  // ============================================
  PLACEHOLDER_CODE_BODY
  
  
  // TESTING CODE 
  // ============================================
  def validateSolution(actual: Int , expected: Int): Boolean = {
      actual.toString == expected.toString
  }
  
  def driver(arr: List[Int], l: Int, r: Int, x: Int, expected: Int): String = {
      try {
          if (validateSolution(PLACEHOLDER_FN_NAME(arr, l, r, x),expected)) {
              "PASSED"
          } else{
              "FAILED"
          }
      }catch{
          case e: Exception => {e.getClass.getName}
      }
  
  }
  object QuestionEvaluator extends App {
  
      println(s"TEST-0...${driver(
        List(3, 4, 4, 8, 9, 13, 13, 15, 18, 27, 30, 32, 42, 48, 50, 52, 56, 66, 69, 69, 77, 84, 84, 93), 19, 12, 22, 
        -1    
      )}")   
  
  
      println(s"TEST-1...${driver(
        List(52, -58, -22, -80, 44, -52, -34, 94, -34, -74, 42, 60, -62, 70, 98, 32, 10, 94, 26, 56, -48, -50, 42, 2, 46, 28, -68, -16, -96, -12, 66, -46, 74, -60, -52, 28, -92, -78, 32, 28, 16, 34, 30, -60, -14), 40, 35, 44, 
        -1    
      )}")   
  
  
      println(s"TEST-2...${driver(
        List(0, 1), 1, 1, 1, 
        1    
      )}")   
  
  
      println(s"TEST-3...${driver(
        List(28, 84, 40, 81), 2, 2, 2, 
        -1    
      )}")   
  
  
      println(s"TEST-4...${driver(
        List(-66, -62, -60, -56, -56, -2, 40, 44, 50, 74, 82, 94), 8, 6, 8, 
        -1    
      )}")   
  
  
      println(s"TEST-5...${driver(
        List(1, 0, 0, 0, 0, 1, 0, 1, 0, 1, 1), 7, 7, 10, 
        -1    
      )}")   
  
  
      println(s"TEST-6...${driver(
        List(15, 26, 31, 36, 36, 61, 68, 72, 75, 79, 82, 98), 6, 7, 8, 
        -1    
      )}")   
  
  
      println(s"TEST-7...${driver(
        List(0, -82, -94, 48, 48, -96, 14, 66, 76, -30, 86, 28, -28, -66, -64, 92, -94, -66, 86, 26, 8, 94, -82, -80, 4, -26, 76, -46, 72, 88, -6, 8, -30, 40, -88, 2, -40, -98, -22, -20, 4, -12, 54, -20, -36, 12), 38, 33, 39, 
        -1    
      )}")   
  
  
      println(s"TEST-8...${driver(
        List(0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1), 12, 10, 6, 
        -1    
      )}")   
  
  
      println(s"TEST-9...${driver(
        List(81, 47), 1, 1, 1, 
        -1    
      )}")   
  
  }
  
source_py: def binary_search(arr, l, r, x):
      if (r >= l):
          mid = (l + ((r - l) // 2))
          if (arr[mid] == x):
              return mid
          elif (arr[mid] > x):
              return binary_search(arr, l, (mid - 1), x)
          else:
              return binary_search(arr, (mid + 1), r, x)
      else:
          return (- 1)
source_cpp: int binary_search(vector<int> arr, int l, int r, int x) {
    if ( r >= l ) {
      int mid = l + ( r - l ) / 2;
      if ( arr [ mid ] == x ) return mid;
      if ( arr [ mid ] > x ) return binary_search ( arr, l, mid - 1, x );
      return binary_search ( arr, mid + 1, r, x );
    }
    return - 1;
  }