comefrom: <awangdev>217. Contains Duplicate_1.java
code: public boolean containsDuplicate(int[] nums) {
          if (nums == null || nums.length == 0) {
              return false;
          }
          HashSet<Integer> set = new HashSet<>();
          for (int num : nums) {
              if (set.contains(num)) {
                  return true;
              }
              set.add(num);
          }
          return false;
      }
masked: public boolean var_0 ( int [ ] var_1 ) {
    if ( var_1 == null || var_1 . length == 0 ) {
      return false ;
    }
    HashSet < Integer > var_2 = new HashSet < > ( ) ;
    for ( int var_3 : var_1 ) {
      if ( var_2 . contains ( var_3 ) ) {
        return true ;
      }
      var_2 . add ( var_3 ) ;
    }
    return false ;
  }
  