代码1

Runtime: 10 ms, faster than 25.66% of Java online submissions for Largest Number.

class Solution {
    public String largestNumber(int[] num) {
        if(num == null || num.length == 0)
            return "";
        
        // Convert int array to String array, so we can sort later on
        String[] s_num = new String[num.length];
        for(int i = 0; i < num.length; i++)
            s_num[i] = String.valueOf(num[i]);
            
        // Comparator to decide which string should come first in concatenation
        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); // reverse order here, so we can do append() later
            }
         };
        
        Arrays.sort(s_num, comp);
        // An extreme edge case by lc, say you have only a bunch of 0 in your int array
        if(s_num[0].charAt(0) == '0')
            return "0";
            
        StringBuilder sb = new StringBuilder();
        for(String s: s_num)
            sb.append(s);
        
        return sb.toString();
        
    }
}