POJ 3087 Shuffle'm Up

Shuffle'm Up

Time Limit: 1000MS Memory Limit: 65536KTotal Submissions: 7880 Accepted: 3615

Description

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 containingC 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 fromS₂. On top of that chip, is the bottommost chip fromS₁. The interleaving process continues taking the 2^nd chip from the bottom ofS₂ and placing that onS₁₂, followed by the 2^nd chip from the bottom ofS₁ and so on until the topmost chip fromS₁ is placed on top ofS₁₂.

After the shuffle operation, S₁₂ is split into 2 new stacks by taking the bottommostC chips from S₁₂ to form a newS₁ and the topmostC chips from S₁₂ to form a newS₂. The shuffle operation may then be repeated to form a newS₁₂.

For this problem, you will write a program to determine if a particular resultant stackS₁₂ 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 integerC, (1 ≤ C ≤ 100) which is the number of chips in each initial stack (S₁ andS₂). The second line of each dataset specifies the colors of each of theC chips in stack S₁, starting with the bottommost chip. The third line of each dataset specifies the colors of each of theC chips in stack S₂ starting with the bottommost chip. Colors are expressed as a single uppercase letter (A throughH). 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 thoughN), 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

24AHAHHAHAHHAAAAHH3CDECDEEEDDCC

Sample Output

1 22 -1

Source

Greater New York 2006

模拟一下洗牌的过程，用map<string,bool>vis 记录状态。

#include <cstdio>#include <iostream>#include <algorithm>using namespace std;#include <cstring>#include <map>int main(){    int t;    scanf("%d",&t);    int num=0;    int i,j,k;    while(t--)    {        num++;        int c;        cin>>c;        char s1[1005];        char s2[1005];        char s3[2010];        char s4[4020];        cin>>s1>>s2>>s3;        map<string,bool>vis;        vis.clear();        vis[s3]=1;        int step=0;        while(1)        {            int len=0;            for(i=0; i<c; i++)            {                s4[len++]=s2[i];                s4[len++]=s1[i];            }            s4[len]='\0';            step++;            if(!strcmp(s4,s3))            {                cout<<num<<" "<<step<<endl;                break;            }            if(vis[s4]&&strcmp(s4,s3))            {                cout<<num<<" "<<-1<<endl;                break;            }            vis[s4]=1;            for(i=0; i<c; i++)                s1[i]=s4[i];            s1[i]='\0';            for(j=0; i<c*2; j++,i++)                s2[j]=s4[i];            s2[j]='\0';        }    }    return 0;}