comefrom: <awangdev>387. First Unique Character in a String_3.java
code: public int firstUniqChar(String s) {
          if (s == null || s.length() == 0) return -1;
          Map<Character, Integer> map = new HashMap<>();
          for (int i = 0; i < s.length(); i++) {
              char c = s.charAt(i);
              map.putIfAbsent(c, 0);
              map.put(c, map.get(c) + 1);
          }
          
          for (int i = 0; i < s.length(); i++) {
              char c = s.charAt(i);
              if (map.get(c) == 1) return i;
          }
          return -1;
      }
masked: public int sample_funcname ( String var_0 ) {
    if ( var_0 == null || var_0 . length ( ) == 0 ) return - 1 ;
    Map < Character , Integer > var_1 = new HashMap < > ( ) ;
    for ( int var_2 = 0 ;
    var_2 < var_0 . length ( ) ;
    var_2 ++ ) {
      char var_3 = var_0 . charAt ( var_2 ) ;
      var_1 . putIfAbsent ( var_3 , 0 ) ;
      var_1 . put ( var_3 , var_1 . get ( var_3 ) + 1 ) ;
    }
    for ( int var_2 = 0 ;
    var_2 < var_0 . length ( ) ;
    var_2 ++ ) {
      char var_3 = var_0 . charAt ( var_2 ) ;
      if ( var_1 . get ( var_3 ) == 1 ) return var_2 ;
    }
    return - 1 ;
  }
  