Finds reverse of given num x .
static int reverseNum ( int x ) { String s = Integer . toString ( x ) ; String str = " " ; for ( int i = s . length ( ) - 1 ; i >= 0 ; i -- ) { str = str + s . charAt ( i ) ; } int rev = Integer . parseInt ( str ) ; return rev ; } static boolean isMysteryNumber ( int n ) { for ( int i = 1 ; i <= n / 2 ; i ++ ) {