public static void main(String args[]){
        MinimumEditForReversePolishNotation mef = new MinimumEditForReversePolishNotation();
        System.out.println(mef.minimum("xxxx*x*x*".toCharArray()));
    }
http://www.careercup.com/question?id=5762415492857856
src/com/interview/recursion/MinimumEditForReversePolishNotation.java