[leedcode 179] 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.

public class Solution {
    public String largestNumber(int[] nums) {
        //注意comp函数的写法，需要继承接口
        //以及Arrays.sort参数的写法，需要把整数形式转化成字符串
        //最后拼接res时，要从后向前拼接
        //最后需要处理首位为0的情况
        StringBuilder res=new StringBuilder();
        if(nums==null||nums.length<=0) return res.toString();
        String[] strs=new String[nums.length];
        for(int i=0;i<nums.length;i++){
            strs[i]=""+nums[i];
        }
       Arrays.sort(strs, new myComparator());
       
        for(int i=nums.length-1;i>=0;i--){
            res.append(strs[i]);
        }
        int i=0;//注意0,0,0的输入
        while(i<res.length()-1&&res.charAt(i)=='0')i++;
        
        return res.toString().substring(i);
    }
     public class  myComparator implements Comparator<String>{
       public int compare(String a,String b){
          return (a+b).compareTo(b+a);
       }  
}      
}