Function returns true if s1 is suffix of s2
static boolean isSuffix ( String s1 , String s2 ) { int n1 = s1 . length ( ) , n2 = s2 . length ( ) ; if ( n1 > n2 ) return false ; for ( int i = 0 ; i < n1 ; i ++ ) if ( s1 . charAt ( n1 - i - 1 ) != s2 . charAt ( n2 - i - 1 ) ) return false ; return true ; }