Substring

 

Problem

Dr lee cuts a string S into N pieces,s[1],…,s[N].   

Now, Dr lee gives you these N sub-strings: s[1],…s[N]. There might be several possibilities that the string S could be. For example, if Dr. lee gives you three sub-strings {“a”,“ab”,”ac”}, the string S could be “aabac”,”aacab”,”abaac”,…   

Your task is to output the lexicographically smallest S. 

 

 

Input

        The first line of the input is a positive integer T. T is the number of the test cases followed.   

The first line of each test case is a positive integer N (1 <=N<= 8 ) which represents the number of sub-strings. After that, N lines followed. The i-th line is the i-th sub-string s[i]. Assume that the length of each sub-string is positive and less than 100. 

 

 

Output

The output of each test is the lexicographically smallest S. No redundant spaces are needed. 

 

 

 

Sample Output

aabac

******************************************************************************************

开学第一节课，系里最牛叉的郭老师就给了六条题，不过第一条好像有点水。

要字典顺序最小的连接后的字符串，只要将所有的substring排序后再连接即可。

排序函数sorting用了改编版的冒泡。

#include <string>
#include <iostream>

using namespace std ;

int T;
void sorting(string data[],int length);

int main()
{
 cin>>T;
 for(int i=0;i<T;i++){

 int N;
 cin>>N;
//声明字符串数组
    string*buf_string=new string[N];
//读入字符串
 for(int loop=0;loop<N;loop++){
  cin>>buf_string[loop];
 }
//对字符串排序
 sorting(buf_string,N);
//将排序后的字符串连接
 string mini_string=buf_string[0];
 for(int j=1;j<=N-1;j++){
  mini_string=mini_string+buf_string[j];
 }
 cout<<mini_string<<endl;
 }
 return 0;
}

void sorting(string data[],int length)
{
 string temp;
 for(int i=0;i<=length-1;i++){
  for(int j=i+1;j<=length-1;j++){
   if(data[i]+data[j]>data[j]+data[i]){// 该比较使得substring两两连接后字典顺序最小
    temp=data[i];
    data[i]=data[j];
    data[j]=temp;
   }
  }
 }
 return;
}
 

Sample Input

13aabac