ShortestSequence

ShortestSequence.java

/**
 * Created by mustafaatik on 01/05/2017.
 */
public class ShortestSequence {

    public static void main(String[] args) {
        turnTo("dcabe", "abcde");
        turnTo("abcdefghjk", "kjhgfedcba");
        turnTo("abcdefghjkm", "mkjhgfedcba");
//        EXPECTED OUTPUT
//        dcabe --> abcde: 2 changes needed
//        abcdefghjk --> kjhgfedcba: 9 changes needed
//        abcdefghjkm --> mkjhgfedcba: 10 changes needed
    }

    static int turnTo(String text1, String text2) {
        // text1 and text2 must have the same characters, ("abc", "abm") is not expected.
        StringBuilder s1 = new StringBuilder(text1);
        StringBuilder s2 = new StringBuilder(text2);
        int ops = 0;
        int i = 0;

        while (i < s1.length()) {
            if (s1.charAt(i) != s2.charAt(i)) {
                /**
                 * searching for the right position of s1[i] by traversing s2 from i+i.th char
                 */
                for (int j = i + 1; j < s2.length(); j++) {
                    if (s1.charAt(i) == s2.charAt(j)) {
                        Object temp = s1.charAt(i);
                        s1.deleteCharAt(i);
                        s1.insert(j, temp);
                        ops++;
                    }
                }
            }
            else
                i++;
        }
        System.out.println(text1 + " --> " + text2 + ": " + ops + " changes needed");
        return ops;
    }
}