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