7) Here is a recursive method that returns the smallest character in a string:

// return smallest character in s, e.g. getMinChar("difference") would return 'c'

static char getMinChar(String s) {

if (s.length() == 1) return s.charAt(0);

if (getMinChar(s.substring(1)) > s.charAt(0))

return s.charAt(0);

else

return getMinChar(s.substring(1));

}

The method returns the correct value but it can be extremely slow when s is a long string. Recode getMinChar so that its more efficient by reducing the number of recursive calls. Your code should still be recursive. There is no need to make major changes to the algorithm.