question: public boolean isTrivial ( Integer complexity ) { int len = payload . length ; if ( ( null == complexity ) || ( len < 2 ) ) { return true ; } else if ( ( complexity . intValue ( ) > 0 ) && ( len > 2 ) ) { Set < Character > seen = new TreeSet < Character > ( ) ; for ( int i = 0 ; i < len ; i ++ ) { Character c = Character . valueOf ( this . payload [ i ] ) ; if ( seen . contains ( c ) ) { continue ; } else { seen . add ( c ) ; } } if ( complexity . intValue ( ) <= seen . size ( ) ) { return false ; } } return true ; }
target:  Check the complexity of the string.