把数组排成最小的数

链接：https://www.nowcoder.com/questionTerminal/8fecd3f8ba334add803bf2a06af1b993
来源：牛客网

 * 解题思路：
 * 先将整型数组转换成String数组，然后将String数组排序，最后将排好序的字符串数组拼接出来。关键就是制定排序规则。
 * 排序规则如下：
 * 若ab > ba 则 a > b，
 * 若ab < ba 则 a < b，
 * 若ab = ba 则 a = b；
 * 解释说明：
 * 比如 "3" < "31"但是 "331" > "313"，所以要将二者拼接起来进行比较
public String PrintMinNumber(int [] numbers) {
        if(numbers == null || numbers.length == 0) return "";
        int len = numbers.length;
        String[] str = new String[len];
        StringBuilder sb = new StringBuilder();
        for(int i = 0; i < len; i++){
            str[i] = String.valueOf(numbers[i]);
        }
        Arrays.sort(str,new Comparator<String>(){
            @Override
            public int compare(String s1, String s2) {
                String c1 = s1 + s2;
                String c2 = s2 + s1;
                return c1.compareTo(c2);
            }
        });
        for(int i = 0; i < len; i++){
            sb.append(str[i]);
        }
        return sb.toString();
    }

链接：https://www.nowcoder.com/questionTerminal/8fecd3f8ba334add803bf2a06af1b993
来源：牛客网

// 利用lambda的简洁解法
import java.util.*;
public class Solution {
    public String PrintMinNumber(int [] numbers) {
        String[] strs = new String[numbers.length];
        for(int i = 0; i < numbers.length; i++)
            strs[i] = String.valueOf(numbers[i]);
        return Arrays.stream(strs)
                    .sorted((x, y) -> (x + y).compareTo(y + x))
                    .reduce("", (x, y) -> x + y);
    }
}

import java.util.ArrayList;

public class Solution {
    public String PrintMinNumber(int [] numbers) {
        String[] str = new String[numbers.length];
        String temp = null;
        for(int i=0;i<numbers.length;i++){
            str[i] = String.valueOf(numbers[i]);
        }
        for(int i=0;i<str.length;i++){
            for(int j=i;j<str.length;j++){
                if(compare(str[i],str[j])>0){
                      temp = str[i];
                      str[i] = str[j];
                      str[j] = temp;
                }
            }
        }
         StringBuffer sb = new StringBuffer();
        for(int i=0;i<str.length;i++){
            sb.append(str[i]);
        }
        return sb.toString();

    }
    public int compare(String s1,String s2){
        String a = s1+s2;
        String b = s2+s1;
        return a.compareTo(b);
    }
  
}