Java Substring Comparisons Hackerrank

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

Function Description

Complete the getSmallestAndLargest function in the editor below.

getSmallestAndLargest has the following parameters:

• string s: a string
• int k: the length of the substrings to find

Returns

• string: the string ' + "\n" + ' where and are the two substrings

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]).

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.

 Approach1:

public static String getSmallestAndLargest(String s, int k) {
        String smallest = "";
        String largest = "";

        String[] list = new String[s.length() - k + 1];
        for (int i = 0; i <= s.length() - k; i++) {
            String str = s.substring(i, i+k);
            list[i] = str;
        }

        smallest = list[0];
        largest = list[0];
        for(int i = 1; i < list.length; i++) {
            if (list[i].compareTo(smallest) < 0) {
                smallest = list[i];
            }

            if (list[i].compareTo(largest) > 0){
                largest = list[i];
            }
        }

        return smallest + "\n" + largest;
    }

Approach 2:

public static String getSmallestAndLargest(String s, int k) {
        String smallest = "";
        String largest = "";
        
        // Complete the function
        // 'smallest' must be the lexicographically smallest substring of length 'k'
        // 'largest' must be the lexicographically largest substring of length 'k'
          java.util.List<String> a = new java.util.ArrayList<>();
        for(int i=0;i<s.length()-k+1;i++){
                a.add(s.substring(i,i+k));   
        }
        java.util.Collections.sort(a);
         smallest = a.get(0);
         largest = a.get(a.size()-1);
        return smallest + "\n" + largest;
    }