HDU 1226 超级密码

#include<iostream>  
#include<queue>  
#include<string>  
using namespace std;  
int n,c,m;  
int a[20];  
int flag;  
bool visited[5100];  
string ans;  
struct node{  
	string ans;  
	int mod;  
}now;  
void bfs(){  
	queue<node> q;  
	int i;  
	for(i=1;i<16;i++)
	{  
		if(a[i])
		{  
			visited[i%n]=1;  
			if(i<10)
			{  
				now.ans="";      now.ans=i+'0';  now.mod=i%n;    q.push(now);  
			}  
			else
			{  
				now.ans="";      now.ans='A'+i-10 ;  now.mod=i%n;    q.push(now);  
			}  
		}  
	}  

	while(!q.empty())
	{  
		now=q.front();  q.pop();  

		if(flag && now.ans.size() > ans.size()) continue;  
		if(now.mod==0)
		{  
			if(!flag)  ans=now.ans;  
			flag=1;  


			if(ans.size()>now.ans.size() || (ans.size()==now.ans.size() && ans>now.ans))
			{  
				ans=now.ans;           
			}  

		}  

		for(i=0;i<16;i++)
		{  
			if(a[i])
			{  
				if(i<10)
				{  
					node next=now;  

					next.ans+=(i+'0');  
					next.mod=(now.mod*c+i)%n;  

					if((next.ans.size()<=500&&!visited[next.mod])||next.mod==0)
					{  
						visited[next.mod]=1;  
						q.push(next);  
					}  
				}  
				else
				{  
					node next=now;  
					next.ans+=('A'+i-10);    
					next.mod=(now.mod*c+i)%n;  

					if((next.ans.size()<=500&&!visited[next.mod])||next.mod==0)
					{  
						visited[next.mod]=1;  
						q.push(next);  
					}  
				}  
			}  
		}  
	}  
}  
int main()
{  
	int t,i;  
	cin>>t;  

	while(t--){  
		char str;  
		scanf("%d%d%d",&n,&c,&m);  
		getchar();  
		memset(a,0,sizeof(a));  
		memset(visited,0,sizeof(visited));  
		for(i=0;i<m;i++) {  
			scanf("%c",&str);  
			if(str>='0'&&str<='9'){  
				a[str-'0']=1;  
			}  
			else{  
				a[str-'A'+10]=1;  
			}  
			getchar();  
		}  

		flag=0;  ans="";  

		if(n==0){  
			if(a[0]==1)  
				cout<<0<<endl;  
			else  
				cout<<"give me the bomb please"<<endl;  
			continue;  
		}  

		bfs();  


		if(flag){  
			cout<<ans<<endl;  
		}  
		else  
			cout<<"give me the bomb please"<<endl;  
	}  
	return 0;  

}