专题测试三 贪心与动态规划 G - Children's Game

1. 题目
   There are lots of number games for children. These games are pretty easy to play but not so easy to
   make. We will discuss about an interesting game here. Each player will be given N positive integer.
   (S)He can make a big integer by appending those integers after one another. Such as if there are
   4 integers as 123, 124, 56, 90 then the following integers can be made — 1231245690, 1241235690,
   5612312490, 9012312456, 9056124123, etc. In fact 24 such integers can be made. But one thing is sure
   that 9056124123 is the largest possible integer which can be made.
   You may think that it’s very easy to find out the answer but will it be easy for a child who has just
   got the idea of number?
   Input
   Each input starts with a positive integer N (≤ 50). In next lines there are N positive integers. Input
   is terminated by N = 0, which should not be processed.
   Output
   For each input set, you have to print the largest possible integer which can be made by appending all
   the N integers.
   Sample Input
   4
   123 124 56 90
   5
   123 124 56 90 9
   5
   9 9 9 9 9
   0
   Sample Output
   9056124123
   99056124123
   99999
2. 思路
   对于每两个数，只有ab和ba两种排序方式，例如90和9只能排成909或者990，对每个这样的组合进行比较排出顺序，最后出来的排列就是最大的
3. 代码
   

   #include<cstdio>
   #include<iostream>
   #include<string>
   #include<cstring>
   #include<algorithm>
   using namespace std;
   
   bool cmp(string &s, string &t)
   {
   	string st = s + t;
   	string ts = t + s;
   	return st > ts;
   }
   
   int main()
   {
   	int n;
   	while (cin >> n && n)
   	{
   		string s[55];
   		int i;
   		for (i = 0; i < n; i++)
   		{
   			cin >> s[i];
   		}
   		sort(s, s+n, cmp);
   		for (i = 0; i < n; i++)
   		{
   			cout << s[i];
   		}
   		cout << endl;
   	}
   	return 0;
   }