Java Substring Comparisons

We define the following terms:

• Lexicographical Order, also known as alphabetic or dictionary order, orders characters as follows:
  For example, ball < cat, dog < dorm, Happy < happy, Zoo < ball.
• A substring of a string is a contiguous block of characters in the string. For example, the
•  substrings of abc are a, b, c, ab, bc, and abc.

Given a string, , and an integer, , complete the function so that it finds the lexicographically
smallest and largest substrings of length .

Input Format

The first line contains a string denoting .
The second line contains an integer denoting .

Constraints

•  consists of English alphabetic letters only (i.e., [a-zA-Z]).

Output Format

Return the respective lexicographically smallest and largest substrings as a single
newline-separated
 string.

Sample Input 0

welcometojava
3

Sample Output 0

ava
wel

Explanation 0

String  has the following lexicographically-ordered substrings of length :

We then return the first (lexicographically smallest) substring and the last (lexicographically largest)

substring as two newline-separated values (i.e., ava\nwel).

The stub code in the editor then prints ava as our first line of output and wel as our second line of
output.

Solution:

import java.util.Scanner;

public class Solution {
    public static String getSmallestAndLargest(String s, int k) {

        String smallest = "";

        String largest = "";

        StringBuffer sb = new StringBuffer();

       for(int i=0; i<s.length()-(k-1); i++){

        sb.append(s.substring(i,i+k)+" ");

       }

       String str = sb.toString();

       String arr[] = str.split(" ");

       java.util.Arrays.sort(arr);

       smallest = arr[0];

       largest = arr[arr.length-1];

       return smallest + "\n" + largest;

    }

    public static void main(String[] args) {

        Scanner scan = new Scanner(System.in);

        String s = scan.next();

        int k = scan.nextInt();

        scan.close();

        System.out.println(getSmallestAndLargest(s, k));

    }

}