南邮 OJ 1125 Substring

Substring

时间限制(普通/Java) :  2000 MS/ 6000 MS          运行内存限制 : 65536 KByte
总提交 : 201            测试通过 : 49 

比赛描述

Dr lee cuts a string S into N pieces , s[1],……,s[N].
Now , Dr lee gives you these N sub-string:s[1]…,s[N].T 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.

输入

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.

输出

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

样例输入

1
3
a
ab
ac

样例输出

aabac

题目来源

第九届中山大学程序设计竞赛预选题

#include<iostream>
#include<string>
#include<vector>
#include<algorithm>
using namespace std;

int main(){
	int T,N,i;
	string s,min_s,ss[8];
	vector<string>::iterator it;
	cin>>T;
	while(T--){
		cin>>N;
		min_s = "~";
		for(i=0;i<N;++i){
			cin>>ss[i];
		}
		sort(ss,ss+N);
		do{
			s = ss[0];
			for(i=1;i<N;++i){
				s += ss[i];
			}
			if(min_s>s){
				min_s = s;
			}
		}while(next_permutation(ss,ss+N));
		cout<<min_s<<endl;
	}
}