Decrease the current value by 1 and repeat the similar checkings
st . setCharAt ( i , ( char ) ( ch - 1 ) ) ; if ( st . charAt ( i ) < '0' ) st . setCharAt ( i , '9' ) ; if ( st . toString ( ) . equals ( target ) ) return count ; if ( ! avoid . contains ( st . toString ( ) ) ) qu . add ( st . toString ( ) ) ; avoid . add ( st . toString ( ) ) ;