hdu 1501(dfs)

#include <iostream>
#include<cstdio>
#include <queue>
#include<string.h>
using namespace std;
const int N=210;
bool mark[N][N];
char s[2*N],s1[N],s2[N];
int len,len1,len2,flag;
void dfs(int i,int j,int k)
{
    if (k>=len) {flag=true;return ;}
    if (mark[i][j]) return ;
    else mark[i][j]=1;
    if (i<len1 && s1[i]==s[k] && flag==0) dfs(i+1,j,k+1);
    if (j<len2 && s2[j]==s[k] && flag==0) dfs(i,j+1,k+1);
}
int main()
{
    int n;
    scanf("%d",&n);
    for (int i=1;i<=n;i++)
    {
        scanf("%s%s%s",s1,s2,s);
        len=strlen(s);
        len1=strlen(s1);
        len2=strlen(s2);
        memset(mark,0,sizeof(mark));
        flag=false;
        dfs(0,0,0);
        if (flag) printf("Data set %d: yes\n",i);
        else printf("Data set %d: no\n",i);
    }
}