时间效率：把数组排成最小的数

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;

public class Solution {
    public String PrintMinNumber(int [] numbers) {
        int n;
        String s = "";
        ArrayList<Integer> list = new ArrayList<Integer>();
        n = numbers.length;
        for (int i = 0; i < n; i++) {
            list.add(numbers[i]);

        }
        Collections.sort(list, new Comparator<Integer>() {
            public int compare(Integer str1, Integer str2) {
                String s1 = str1 + "" + str2;
                String s2 = str2 + "" + str1;
                return s1.compareTo(s2);
            }
        });

        for (int j : list) {
            s += j;
        }
        return s;
    }
}