title: Find The Number Occurring Odd Number Of Times 1
signature: function find_the_number_occurring_odd_number_of_times_1(arr, size)
test_code: 
  
  -- SOLUTION CODE
  -- ============================================
  PLACEHOLDER_CODE_BODY
  
  -- TESTING CODE 
  -- ============================================
  function isCorrect(actual, expected)
      if type(expected) ~= type(actual) then
          return false
      end
      
      if type(expected) == 'table' then
          for k,v_expected in pairs(expected) do
              
              if actual[k] == nil then
                  return false
              end
              local v_actual = actual[k]
              if not isCorrect(v_actual, v_expected) then
                  return false
              end
              actual[k]=nil
          end
      
          if next(actual) then 
              return false
          end
          return true
      else
          return actual == expected
      end
  end
  
  function validateSolution(actual, expected)
      return isCorrect(actual,expected)
  end
  
  function driver(arr, size, expected)
      local exec_result;
      local status, error_msg = pcall(function () 
          exec_result=PLACEHOLDER_FN_NAME(arr, size) 
      end)
      if status then
          if validateSolution(exec_result,expected) then
              return "PASSED"
          end
          return "FAILED"
      else
          return string.format("ERROR=%s",string.gsub(error_msg,".*:[%d]+: ",""))
      end
  end
      
  function main()
      result = driver({49, 90}, 1, 49)
      print(string.format("TEST-0...%s",result))
  
      result = driver({-96, 94, 92, -24, 48, 54, -30, -86, 28, -18, 12, -64, -36, 68, 68, -78, -6, 30, -84, 20, 52, -36, 40, -62, 90, -48, 86, 98, 12, 44, 98, -66, 52, 34, 36, 76, -50, -20, -20, -20}, 39, -96)
      print(string.format("TEST-1...%s",result))
  
      result = driver({0, 1}, 1, 0)
      print(string.format("TEST-2...%s",result))
  
      result = driver({79, 55, 18, 99, 38, 93, 19, 49, 21, 74, 16, 76, 82, 52, 86, 17, 42, 9, 6, 63, 1, 40, 75, 59, 41, 81}, 23, 79)
      print(string.format("TEST-3...%s",result))
  
      result = driver({-90, -84, -82, -68, -66, -66, -60, -60, -48, -44, -36, -34, -30, -16, -14, -12, -10, -6, 2, 10, 10, 14, 22, 26, 30, 34, 46, 50, 52, 62, 64, 64, 66, 72, 74, 78, 78, 82, 84, 88, 92}, 23, -90)
      print(string.format("TEST-4...%s",result))
  
      result = driver({1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 1, 1, 0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 0, 1}, 18, 1)
      print(string.format("TEST-5...%s",result))
  
      result = driver({2, 4, 5, 7, 7, 18, 18, 23, 23, 25, 25, 31, 41, 43, 45, 46, 52, 52, 55, 64, 69, 69, 80, 81, 84, 90, 91, 93, 94, 94, 94, 94, 96, 98, 99}, 20, 2)
      print(string.format("TEST-6...%s",result))
  
      result = driver({86, 66, -8, 2, -18, -22, 38, 4, -38, -54, 78, 64, 78, 20, -32, 84, -70, 66, -46, 12, -12, 8, 44, 14, 20}, 20, 86)
      print(string.format("TEST-7...%s",result))
  
      result = driver({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}, 21, 0)
      print(string.format("TEST-8...%s",result))
  
      result = driver({11, 4, 98, 38, 20, 41, 1, 8}, 7, 11)
      print(string.format("TEST-9...%s",result))
  
  end
  
  main()
source_py: def find_the_number_occurring_odd_number_of_times_1(arr, size):
      Hash = dict()
      for i in range(size):
          Hash[arr[i]] = (Hash.get(arr[i], 0) + 1)
      for i in Hash:
          if ((Hash[i] % 2) != 0):
              return i
      return (- 1)
source_cpp: int find_the_number_occurring_odd_number_of_times_1(vector<int> arr, int size) {
    unordered_map < int, int > hash;
    for ( int i = 0;
    i < size;
    i ++ ) {
      hash [ arr [ i ] ] ++;
    }
    for ( auto i : hash ) {
      if ( i . second % 2 != 0 ) {
        return i . first;
      }
    }
    return - 1;
  }