11. [Technical Interview] Given a list of non negative integers, arrange them such that they form the largest number.

Given a list of non negative integers, arrange them such that they form the largest number.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

import java.util.*; public class HelloWorld{ public static void main(String []args){ int[] testIntArray = {3, 30}; System.out.println(largestNumber(testIntArray)); } public static String largestNumber(int[] nums) { String result = ""; String[] numAsStringsArray = new String[nums.length]; for (int i = 0; i < nums.length; i++) { numAsStringsArray[i] = Integer.toString(nums[i]); } // The lambda expression must be (str1, str2) -> (str2 + str1).compareTo(str1 + str2) // because you are comparing str2 to str1. For example, str1 is 3 and str2 is 30. // so we must do (str2 + str1).compareTo(str1 + str2) and not (str1 + str2).compareTo(str2 + str1) // because we are comparing str2 to str1, so str2 must come before str1 so it will look like // 303 compare to 330, compareTo does natural order in ascending order so we want this way Arrays.sort(numAsStringsArray, (str1, str2) -> (str2 + str1).compareTo(str1 + str2)); if (numAsStringsArray[0].equals("0")) { return "0"; } StringBuilder sb = new StringBuilder(); for (String str : numAsStringsArray) { sb.append(str); } return sb.toString(); } }