lintcode-medium-Largest Number

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

 

Given [1, 20, 23, 4, 8], the largest formed number is 8423201.

 

public class Solution {
    /**
     *@param num: A list of non negative integers
     *@return: A string
     */
    public String largestNumber(int[] num) {
        // write your code here
        
        if(num == null || num.length == 0)
            return "";
        
        String[] strs = new String[num.length];
        for(int i = 0; i < num.length; i++)
            strs[i] = String.valueOf(num[i]);
        
        Arrays.sort(strs, new Comparator<String>(){
            public int compare(String s1, String s2){
                
                return (s2 + s1).compareTo(s1 + s2);
            }
        });
        
        StringBuilder result = new StringBuilder();
        for(int i = 0; i < strs.length; i++)
            result.append(strs[i]);
        
        while(result.length() > 1 && result.charAt(0) == '0')
            result.deleteCharAt(0);
        
        return result.toString();
    }
}