import java.util.*;

public class Main {

	static double bestP=0.0;
	public static void main(String[] args) {
		// TODO 自动生成方法存根
      
        	Scanner input=new Scanner(System.in);
        	while(true)
        	{
        		int n=input.nextInt();
        		int t=input.nextInt();
        		int l=input.nextInt();
        		int b=input.nextInt();
        		if(n==0&&t==0&&l==0&&b==0) break;
        		int lost[]=new int[l+1];
        		int back[]=new int[b+1];
        		for(int i=0;i<l;++i)
        			lost[i]=input.nextInt();
        		for(int i=0;i<b;++i)
        			back[i]=input.nextInt();
        		new Main().solve(n,t,l,b,lost,back);
        	}
	}
	static void DFS(int n,int t,int l,int b,int lost[],int back[],int count,double p,int pos)
	{
		int j;
		if(count>=t)
		{
			if(count==t&&pos==n) 
			{
				bestP+=p;
				return;
			}
			return;
		}
	    if(count<t)
		{
		   for(int i=1;i<=6;++i)
			{ 
			    j=pos+i;
				if((pos+i)>n) j=n+n-j;
				if(j==n)
				  {  
					  bestP+=(p/6);
					  continue;
				  }
				boolean flagL=false;
				boolean flagB=false;
				for(int k=0;k<l;++k)
				{
					if(lost[k]==j)
					{
						flagL=true;
						break;
					}
				}
				if(flagL)
				{
					DFS(n,t,l,b,lost,back,count+2,p/6,j);
					continue;
		        }
				for(int k=0;k<b;++k)
				{
					if(back[k]==j)
				    {
				     flagB=true;
							break;
				     }
				}
				if(flagB)
				{
				    DFS(n,t,l,b,lost,back,count+1,p/6,0);
				    continue;
				}
				DFS(n,t,l,b,lost,back,count+1,p/6,j);	
			}	
		}
	}
	static void solve(int n,int t,int l,int b,int lost[],int back[])
	{
		bestP=0.0;
		DFS(n,t,l,b,lost,back,0,1,0);
		System.out.println(bestP);
	}

}

• Re:Help!why runtime error?thanks! (18) allencxz 2008-03-11 22:33:51
  • 那位大牛帮忙看一下啊，谢谢了！！自顶！！ (22) allencxz 2008-03-13 21:58:03