title: Non Repeating Element
signature: function non_repeating_element(arr, n)
test_code: using Printf
  
  # SOLUTION CODE
  # ============================================
  PLACEHOLDER_CODE_BODY
  
  # TESTING CODE 
  # ============================================
  function validate_solution(actual, expected)
      return actual == expected
  end
  
  function driver(arr, n, expected)
      try
  
          if validate_solution(PLACEHOLDER_FN_NAME(arr, n), expected)
              return "PASSED";
          end
          return "FAILED";
      catch exception_obj
          return string(Base.typename(typeof(exception_obj)).wrapper);
      end
  end
  
  function main()
      
      result = driver([1, 2, 3, 4, 6, 6, 7, 9, 10, 13, 16, 23, 30, 32, 36, 42, 42, 43, 44, 47, 48, 48, 49, 52, 52, 53, 55, 56, 58, 59, 60, 60, 63, 67, 68, 68, 74, 75, 76, 80, 81, 81, 83, 83, 86, 87, 91, 92, 97], 47, 1);
      @printf("TEST-0...%s\n",result);
      
      result = driver([-96, -46, -86, 56, -72, 50, 18, 8, 50], 8, -96);
      @printf("TEST-1...%s\n",result);
      
      result = driver([0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1], 14, -1);
      @printf("TEST-2...%s\n",result);
      
      result = driver([19, 10, 49, 40, 34, 21, 63, 51], 5, 19);
      @printf("TEST-3...%s\n",result);
      
      result = driver([-96, -96, -90, -88, -88, -84, -80, -76, -68, -64, -64, -52, -52, -52, -52, -50, -50, -48, -48, -40, -32, -26, -24, -22, -20, -14, -12, 0, 6, 8, 10, 20, 24, 28, 34, 36, 54, 60, 60, 60, 68, 74, 74, 74, 84, 88, 94], 27, -90);
      @printf("TEST-4...%s\n",result);
      
      result = driver([1, 0, 0, 1, 0, 1, 1, 1, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 1, 1, 0, 1, 0, 0, 0], 19, -1);
      @printf("TEST-5...%s\n",result);
      
      result = driver([1, 2, 3, 10, 15, 21, 28, 36, 41, 44, 45, 47, 72, 77, 77, 79, 85], 15, 1);
      @printf("TEST-6...%s\n",result);
      
      result = driver([42, -84, 42, 36, -10, 24, -62, 60], 7, -84);
      @printf("TEST-7...%s\n",result);
      
      result = driver([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1], 35, -1);
      @printf("TEST-8...%s\n",result);
      
      result = driver([2, 21, 42, 92, 65, 62, 75, 43, 81, 17, 92, 86, 37, 63, 27, 97, 24, 61, 85, 49, 84, 7, 14, 19, 60, 55, 68, 79, 8, 12, 75, 12, 92, 79, 42], 27, 2);
      @printf("TEST-9...%s\n",result);
      
  end
  
  main()
source_py: def non_repeating_element(arr, n):
      for i in range(n):
          j = 0
          while (j < n):
              if ((i != j) and (arr[i] == arr[j])):
                  break
              j += 1
          if (j == n):
              return arr[i]
      return (- 1)
source_cpp: int non_repeating_element(vector<int> arr, int n) {
    for ( int i = 0;
    i < n;
    i ++ ) {
      int j;
      for ( j = 0;
      j < n;
      j ++ ) if ( i != j && arr [ i ] == arr [ j ] ) break;
      if ( j == n ) return arr [ i ];
    }
    return - 1;
  }