[Leetcode] Largest Number

再次熟悉java当中的comparator的写法

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.

 

这里的一个Corner case 是我们需要考虑0的出现：

如果全是零，那么返回“0”

如果有零的存在，需要在最后的最大数字的后面append上相应的零。

 

import java.util.*;

public class Solution {
    private class mycompare implements Comparator<String>{
        public int compare(String i1, String i2){
            String i12 = i1+""+i2;
            String i21 = i2+""+i1;
            return -i12.compareTo(i21);
        }
    }
    public String largestNumber(int[] nums) {
        //Arrays.sort(nums,new mycompare());
        Vector<String> strs = new Vector<String>();
        int zerocount=0;
        for(int i: nums){
            if(i==0) zerocount++;
            else strs.add(i+"");
        }
        Collections.sort(strs,new mycompare());
        String res="";
        for(int i=0;i<strs.size();i++){
            res = res + strs.get(i);
        }
        if(strs.size()==0) return "0";
        else{
            for(int i=0;i<zerocount;i++){
                res=res+"0";
            }
        }
        return res;
    }
}