title: Find The Number Occurring Odd Number Of Times
signature: findTheNumberOccurringOddNumberOfTimes(arr, arr_size) {
test_code: import 'dart:convert';
  
  // SOLUTION CODE
  // ============================================
  PLACEHOLDER_CODE_BODY
  
  // TESTING CODE 
  // ============================================
  bool validateSolution(int actual, int expected){
      return actual.toString() == expected.toString();
  }
  
  String driver(arr, arr_size, int expected){
      try
      {
          if (validateSolution(PLACEHOLDER_FN_NAME(arr, arr_size), expected)){
              return "PASSED";
          }
          return "FAILED";
      }catch(exception_object){
          return exception_object.runtimeType.toString();
      }
  }
  
  int main() {
  
      print("TEST-0...${driver(
          [1, 5, 5, 8, 14, 15, 17, 17, 18, 23, 23, 25, 26, 35, 36, 39, 51, 53, 56, 56, 60, 62, 64, 64, 65, 66, 67, 68, 71, 75, 80, 82, 83, 88, 89, 91, 91, 92, 93, 95, 99], 31, 
          1)
      }");
  
      print("TEST-1...${driver(
          [-56, 98, 44, 30, -88, 18, 60, 86, 4, 16, 10, 64, -22, -86, -66, -16, 70, -44, 98, 78, -96, -66, 92, 10, 40, -16], 19, 
          -56)
      }");
  
      print("TEST-2...${driver(
          [0, 0, 0, 0, 0, 1, 1, 1], 6, 
          0)
      }");
  
      print("TEST-3...${driver(
          [36, 11, 83, 41, 42, 14, 46, 89, 91, 96, 57, 42, 74, 73, 9, 26, 79, 40, 31, 69, 44, 39, 14, 92, 34, 20, 52, 47, 14], 25, 
          36)
      }");
  
      print("TEST-4...${driver(
          [-84, -84, -84, -78, -66, -62, -62, -36, -24, -10, -10, -8, -4, -2, 12, 14, 20, 22, 36, 42, 46, 66, 84, 96, 96, 98], 23, 
          -84)
      }");
  
      print("TEST-5...${driver(
          [1, 1, 0, 1, 0, 1, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1], 19, 
          1)
      }");
  
      print("TEST-6...${driver(
          [11, 12, 14, 28, 42, 48, 50, 58, 67, 74, 86, 89, 95], 7, 
          11)
      }");
  
      print("TEST-7...${driver(
          [52, -56, -6, 74, 10, 68, 74, 10, 16, -80, 82, -32, 6, -6, 82, 20], 11, 
          52)
      }");
  
      print("TEST-8...${driver(
          [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, 1, 1, 1, 1, 1, 1, 1], 31, 
          0)
      }");
  
      print("TEST-9...${driver(
          [4, 80, 92], 1, 
          4)
      }");
  
      return 0;
  }
source_py: def find_the_number_occurring_odd_number_of_times(arr, arr_size):
      for i in range(0, arr_size):
          count = 0
          for j in range(0, arr_size):
              if (arr[i] == arr[j]):
                  count += 1
          if ((count % 2) != 0):
              return arr[i]
      return (- 1)
source_cpp: int find_the_number_occurring_odd_number_of_times(vector<int> arr, int arr_size) {
    for ( int i = 0;
    i < arr_size;
    i ++ ) {
      int count = 0;
      for ( int j = 0;
      j < arr_size;
      j ++ ) {
        if ( arr [ i ] == arr [ j ] ) count ++;
      }
      if ( count % 2 != 0 ) return arr [ i ];
    }
    return - 1;
  }