title: Find The Number Occurring Odd Number Of Times 1
signature: def findTheNumberOccurringOddNumberOfTimes1(arr: List[Int], size: Int) = {
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;
  }