179. Largest Number

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LeetCode

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Problem

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

Example 1:

Input: [10,2]
Output: "210"

Example 2:

Input: [3,30,34,5,9]
Output: "9534330"

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

Code

class Solution {
     public String largestNumber(int[] num) {
		if(num == null || num.length == 0)
		    return "";

		String[] s_num = new String[num.length];
		for(int i = 0; i < num.length; i++){
		    s_num[i] = String.valueOf(num[i]);
		}

		Comparator<String> comp = new Comparator<String>(){
		    @Override
		    public int compare(String str1, String str2){
		        String s1 = str1 + str2;
			    String s2 = str2 + str1;
			    return s2.compareTo(s1);
		    }
	    };

		Arrays.sort(s_num, comp);

		if(s_num[0].equals("0")) return "0";

		StringBuilder sb = new StringBuilder();
		for(String s: s_num){
		  sb.append(s);
		}

		return sb.toString();
	}
}