# 几何平方距离的判断，输出的序列式怎么算，采用C程序的方式

Problem Description
A string is called a square string if it can be obtained by concatenating two copies of the same string. For example, "abab", "aa" are square strings, while "aaa", "abba" are not.

Hamming distance between two strings of equal length is the number of positions at which the corresponding symbols are different.

Peter has a string s=s1s2...sn of even length. He wants to find a lexicographically smallest square string t=t1t2...tn that the hamming distance between s and t is exact m. In addition, both s and t should consist only of lowercase English letters.

Input
There are multiple test cases. The first line of input contains an integer T, indicating the number of test cases. For each test case:

The first contains two integers n and m (1≤n≤1000,0≤m≤n,n is even) -- the length of the string and the hamming distance. The second line contains the string s.

Output
For each test case, if there is no such square string, output "Impossible" (without the quotes). Otherwise, output the lexicographically smallest square string.

Sample Input
3
4 1
abcd
4 2
abcd
4 2
abab

Sample Output
Impossible
abab
aaaa

• 写回答

#### 1条回答默认 最新

• threenewbee 2020-01-07 01:33
关注
本回答被题主选为最佳回答 , 对您是否有帮助呢?
评论

#### 悬赏问题

• ¥30 使用C++实现ATM系统
• ¥20 求帮，直连能连上oracle12，但是thinkphp6就是报错
• ¥15 paddleocr运行报错
• ¥15 怎么用 matlab 设计滞后-超前串联校正网络
• ¥15 MFC引用C#生成的dll,将dll放置到非exe程序目录，如何操作
• ¥15 C#创建webservice接口，三方通过多次跳转访问本方服务，获取wsdl文档，wsdl中ip地址为局域网内本机地址而非三方直接访问的地址。
• ¥15 关于#wireshark#的问题：需要安卓app流量数据集要安卓流量做包序列长度的实验，比如某些流量是在看视频还是在发评论
• ¥15 Smail语句如何使用判断语句跳过验证卡密界面
• ¥15 关于#wireshark#的问题：并且能够给数据做标注，如这个流量是在看视频或者是在转账
• ¥15 运筹优化，gurobi,python