title: Non Repeating Element
signature: nonRepeatingElement(arr, n) {
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;
  }