拼接最小字典序

import java.util.*;

public class Prior {

    public String findSmallest(String[] strs, int n) {

        // 这里使用插入排序

        for (int i = 1; i < strs.length; i++) {

            // 当前需要排序的元素

            String target = strs[i];

            // j标记当前位置

            int j = i;

            while(j>0 && (target+strs[j-1]).compareTo(strs[j-1]+target) < 0){

                strs[j] = strs[j-1];

                j--;

            }

            strs[j] = target;

        }

        StringBuffer sb = new StringBuffer();

        for(String str: strs){

            sb.append(str);

        }

        return sb.toString();

    }

    //方法二，使用Arrays.sort()方法

    public String findSmallest2(String[] strs, int n) {

        if(strs == null){

            return null;

        }

        Comparator<String> c = new Comparator<String>() {

            @Override

            public int compare(String str1, String str2) {

                String str1first = str1 + str2;

                String str2first = str2 + str1;

                return str1first.compareTo(str2first);

            }

        };

        Arrays.sort(strs, c);

        StringBuffer str = new StringBuffer();

        for(int i = 0; i < n; i++){

            str.append(strs[i]);

        }

        return str.toString();

    }

}