[hacker_rank] Java String Compare with java

문제: https://www.hackerrank.com/challenges/java-string-compare/problem

public static String getSmallestAndLargest(String s, int k) {
    String largest = s.substring(0, k);
    String smallest = s.substring(0, k);
    for (int i = 0; i <= s.length() - k; i++){
        String curr = s.substring(i, i + k);
        if (curr.compareTo(smallest) < 0)
            smallest = curr;
        if (curr.compareTo(largest) > 0)
            largest = curr;
    }         
    return smallest + "\n" + largest;

}