POJ3087 Shuffle'm Up (strcmp;strcpy;strcat)

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 2nd chip from the bottom of S2 and placing that on S12, followed by the 2nd 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
咋一看没有思路，还以为要用栈来做
题目的意思是给你两个字符串和一个标准串，每次从一个字符串的最前取出一个来，组成一个新字符串，如果不成功，则从形成的新字符串中两头取字符重新造两个字符串（洗牌），若所有洗牌都不成功，就输出-1
需要用到的函数有
strcmp（）：比较两个字符串是否相同，相同则返回0
strcpy（）：将一个字符串复制到另一个
strcat（）：连接两个字符串

#include<iostream>
#include<cstdio>
#include<string.h>
using namespace std;
char card1[520];
char card2[520];
char pipei[1010];
char save[1010];
char ss[1010];
int main()
{

int t,o=0;
scanf("%d",&t);
while(t--)
{ int n;
  o++;
  cin>>n;
  cin>>card1;
  cin>>card2;
  cin>>pipei;
  strcpy(save,card1);//储存两个字符串初始形态
  strcat(save,card2);//
  int ans=0;
  int k;
  while(1)
{
  k=0;
  ans++;
  for(int i=0;i<n;i++)
  {
    ss[k++]=card2[i];
    ss[k++]=card1[i];
  }//构造字符串
  ss[k]='\0';
  if(!strcmp(ss,pipei))//如果标准相同输洗次数
  {
    printf("%d %d\n",o,ans);
    break;
  }
  else//不同则洗牌
  { int i;int j=0;
    for(i=0;i<n;i++)
      card1[i]=ss[i];
    for(;i<2*n;i++)
      card2[j++]=ss[i];
    card1[n]='\0';
    card2[j]='\0';
    if(!strcmp(ss,save))//如果洗牌洗到回到初始状态说不可能
    {printf("%d -1\n",o);
    break;
    }
  }

}}}

还有一种方法是用map储存状态
if(map1.find(s)!=map1.end())
{
break;
}
map1[s]=0; //如果找到了s就break
注：map中每个元素只有唯一的对应值