179. Largest Number

Largest Number

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

For example, given [3, 30, 34, 5, 9], the largest formed number is 9534330.

Note: The result may be very large, so you need to return a string instead of an integer.

Credits:Special thanks to @ts for adding this problem and creating all test cases.

Solution

public class Solution {
     public String largestNumber(int[] nums) {
        List<String> numsStrings = Arrays.stream(nums).mapToObj(String::valueOf).collect(Collectors.toList());

        Collections.sort(numsStrings, (a, b) -> {
            String m = String.valueOf(a);
            String n = String.valueOf(b);

            return Long.compare(new Long(m + n), new Long(n + m));
        });


        StringBuffer sb = new StringBuffer();
        for (int i = numsStrings.size() - 1; i >= 0; i--) {
            sb.append(numsStrings.get(i));
        }


        int i = 0;
        while (i < sb.length() - 1) {
            if (sb.charAt(i) == '0') {
                i++;
            } else {
                break;
            }
        }

        return sb.substring(i);
    }

}