title: Binary Search
signature: binarySearch :: [Integer] -> Integer -> Integer -> Integer -> Integer
  binarySearch arr l r x = 
test_code: import Text.Printf
  import Control.Exception (catch, SomeException)
  import Data.Typeable
  import qualified Data.List as List
  import qualified Data.Map as Map
  import qualified Data.Set as Set
  
  -- SOLUTION CODE
  -- ============================================
  
  PLACEHOLDER_CODE_BODY
  
  -- TESTING CODE 
  -- ============================================
  validateSolution :: Integer -> Integer -> Bool
  validateSolution actual expected = do
      actual == expected
  
  
  driver :: [Integer] -> Integer -> Integer -> Integer -> Integer -> String
  driver arr l r x expected = do
      if (validateSolution (PLACEHOLDER_FN_NAME arr l r x) expected)
          then "PASSED"
      else "FAILED"
  
  main = do
      printf "TEST-0...%s\n" (driver ([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) )
  
      printf "TEST-1...%s\n" (driver ([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) )
  
      printf "TEST-2...%s\n" (driver ([0, 1]) (1) (1) (1) (1) )
  
      printf "TEST-3...%s\n" (driver ([28, 84, 40, 81]) (2) (2) (2) (-1) )
  
      printf "TEST-4...%s\n" (driver ([-66, -62, -60, -56, -56, -2, 40, 44, 50, 74, 82, 94]) (8) (6) (8) (-1) )
  
      printf "TEST-5...%s\n" (driver ([1, 0, 0, 0, 0, 1, 0, 1, 0, 1, 1]) (7) (7) (10) (-1) )
  
      printf "TEST-6...%s\n" (driver ([15, 26, 31, 36, 36, 61, 68, 72, 75, 79, 82, 98]) (6) (7) (8) (-1) )
  
      printf "TEST-7...%s\n" (driver ([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) )
  
      printf "TEST-8...%s\n" (driver ([0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1]) (12) (10) (6) (-1) )
  
      printf "TEST-9...%s\n" (driver ([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;
  }