HDU 1501 Zipper

#include<cstdio>
#include<cstring>
#include<cmath>
#include<queue>
#include<map>
#include<algorithm>
using namespace std;

const int maxn=500;
char s1[maxn],s2[maxn],s[maxn];
struct X
{
int A,B;
X(int a,int b)
{
A=a;
B=b;
}
};

int main()
{
int T; scanf("%d",&T);
for(int Case=1;Case<=T;Case++)
{
memset(s1,0,sizeof s1);
memset(s2,0,sizeof s2);
memset(s,0,sizeof s);

scanf("%s%s%s",s1,s2,s);

queue<X>Q[2]; int now=0;

map<int,bool>m;
int lenA=strlen(s1),lenB=strlen(s2),lenS=strlen(s);

m[0]=1;
Q[now].push(X(0,0));

for(int i=0;s[i];i++)
{
m.clear();
now=now^1;
while(!Q[now^1].empty())
{
X head=Q[now^1].front(); Q[now^1].pop();
if(s1[head.A]==s[i]&&head.B+lenS-i>=lenB&&m[head.A+1]==0){
Q[now].push(X(head.A+1,head.B));
m[head.A+1]=1;
}
if(s2[head.B]==s[i]&&head.A+lenS-i>=lenA&&m[head.A]==0){
Q[now].push(X(head.A,head.B+1));
m[head.A]=1;
}
}
}

int ans=0;

while(!Q[now].empty())
{
X head=Q[now].front(); Q[now].pop();
if(head.A==lenA&&head.B==lenB) ans=1;
}
printf("Data set %d: ",Case);
if(ans==1) printf("yes\n");
else printf("no\n");
}
return 0;
}