poj-3087 Shuffle'm Up

A common pastime for poker players at a poker table is to shuffle stacks of chips. Shuffling chips is performed by starting with two stacks of poker chips, S₁ and S₂, each stack containing C chips. Each stack may contain chips of several different colors.

The actual shuffle operation is performed by interleaving a chip from S₁ with a chip from S₂ as shown below for C = 5:

The single resultant stack, S₁₂, contains 2 * C chips. The bottommost chip of S₁₂ is the bottommost chip from S₂. On top of that chip, is the bottommost chip from S₁. The interleaving process continues taking the 2^nd chip from the bottom of S₂ and placing that on S₁₂, followed by the 2^nd chip from the bottom of S₁ and so on until the topmost chip from S₁ is placed on top of S₁₂.

After the shuffle operation, S₁₂ is split into 2 new stacks by taking the bottommost C chips from S₁₂ to form a new S₁ and the topmost C chips from S₁₂ to form a new S₂. The shuffle operation may then be repeated to form a new S₁₂.

For this problem, you will write a program to determine if a particular resultant stack S₁₂ can be formed by shuffling two stacks some number of times.

Input

The first line of input contains a single integer N, (1 ≤ N ≤ 1000) which is the number of datasets that follow.

Each dataset consists of four lines of input. The first line of a dataset specifies an integer C, (1 ≤ C ≤ 100) which is the number of chips in each initial stack (S₁ and S₂). The second line of each dataset specifies the colors of each of the C chips in stack S₁, starting with the bottommost chip. The third line of each dataset specifies the colors of each of the C chips in stack S₂ starting with the bottommost chip. Colors are expressed as a single uppercase letter (A through H). There are no blanks or separators between the chip colors. The fourth line of each dataset contains 2 * C uppercase letters (A through H), representing the colors of the desired result of the shuffling of S₁ and S₂ zero or more times. The bottommost chip’s color is specified first.

Output

Output for each dataset consists of a single line that displays the dataset number (1 though N), a space, and an integer value which is the minimum number of shuffle operations required to get the desired resultant stack. If the desired result can not be reached using the input for the dataset, display the value negative 1 (−1) for the number of shuffle operations.

Sample Input

2
4
AHAH
HAHA
HHAAAAHH
3
CDE
CDE
EEDDCC

Sample Output

1 2
2 -1

这题的题意好难好难理解啊，我读了半天又看了题解才反应过来。
题意：给你三个字符串s1,s2,s12，规则是将s1和s2进行交叉堆放构成一个新的字符串st，判断这个新的字符串
是否是目标字符串s12，若不是，则把s12平分成两块，最下面的c个构成新的s1，上面的构成新的s2，然后再交叉
堆放构成字符串st，判断是否是目标字符串s12，若还不是，重复以上操作，直到找到或者找不到（出现重复的s12）
为止。拿样例举个例：
S1:AHAH   　　　　　　　　　　　　　　　　　HAAH
　　　　 交叉堆放st为HAAHHAAH!=s12 平分  　　　　　　重复操作……
S2:HAHA　　　　　　　　　　　　　　　　　　 HAAH

知道题意就好理解了，就是道模拟题，附代码。

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <iostream>
#include <map>
using namespace std;
const int M = 211;
char st1[M],st2[M],str[2*M],stu[M*2];
int main(){
	ios::sync_with_stdio(false);
	int t;
	cin>>t;
	for(int k=1;k<=t;k++){
		map<string,bool>mp;
		memset(st1,0,sizeof(st1));
		memset(st2,0,sizeof(st2));
		memset(str,0,sizeof(str));
		memset(stu,0,sizeof(stu));
		int n;
		cin>>n;
		cin>>st1>>st2>>str;
		mp[str]=1; 
		int cnt=0;
		while(1){
			for(int i=0;i<n;i++){
			stu[2*i]=st2[i];
			stu[2*i+1]=st1[i];
			}
			stu[2*n]='';
			cnt++;
			if(!strcmp(stu,str)){
				cout<<k<<" "<<cnt<<endl;
				break;
			}
			else if(mp[stu]&&strcmp(stu,str)){
				cout<<k<<" "<<-1 <<endl;
				break;
			}
			mp[stu]=1;
			
			for(int i=0;i<n;i++){
				st1[i]=stu[i];
			}
			st1[n]='';
			for(int i=n;i<2*n;i++){
				st2[i-n]=stu[i];
			}
			st2[n]='';
		//	cout<<st2<<endl;
		}
	}
	return 0;
}

　这题有个地方我卡了没ac，就是stu数组的大小，我忘了给M*2，交上去说是wa，我找了好久好久啊，就是没找到T T。