POJ3087——map——Shuffle'm Up

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 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

大意：洗牌，每一次洗牌都是选取s2中的再选取s1中的，不断重复，最后分的时候也是先s1再s2，问最少多少次能分完。看了题解，见识了map和string的用法

map：

2 -1

Source

Greater New York 2006

定义：例如：map<string,bool>表示下标定义为string型，值定义为bool型

操作：

1.find(s)   返回指向s的迭代器（迭代器相当于是一个特殊的标识符）.end()返回指向末尾的迭代器，如代码中的m.find(s) == m.end()意思就是如果find(s)的迭代器与end相同，那么就执行（迭代器本身是false），然后这个s就用过了,m[s] = true

2.substr(k,n)   分割子串，k表示起始的下标，n表示长度

string:

定义：字符串

操作：能直接比较和加元素

#include<iostream>
#include<cstring>
#include<map>
#include<cstdio>
#include<string>
using namespace std;
string s1,s2,s12,s;
int l,res;
void shuffle()
{
    s.clear();
    for(int i = 0 ; i < l ; i++){
        s+=s2[i];
        s+=s1[i];
    }
}
int solve()
{
     res = 1;
    map<string, bool> m;
    shuffle();
    if(s == s12)
        return 1;
    while(m.find(s) == m.end()){
            m[s] = true;
            s1 = s.substr(0,l);
            s2 = s.substr(l,l);
            shuffle();
            res++;
            if(s == s12)
                return res;
    }
    return -1;
}
int main()
{
    int  T,count = 1;
    cin >> T;
    while(T--){
        cin >> l;
       cin >> s1 >> s2 >>s12;
       if(solve() != -1)
        printf("%d %d\n",count++,res);
       else printf("%d -1\n",count++);
    }
    return 0;
}

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