ZOJ 3675 Trim the Nails

狀態壓縮+暴搜

trick點：指甲剪可以反着剪

#include<cstdio>
#include<iostream>
#include<cstring>
#include<queue>
using namespace std;
#define LL long long
struct State
{
	int state,step;
	State(int sta=0,int ste=0)
	{
		state=sta;
		step=ste;
	}
};
LL cli1;
LL cli2;
int n,m;
int vis[1<<21];
int bfs()
{
	State tmp;
	memset(vis,0,sizeof(vis));
	queue<State> q;
	q.push(State(0,0));
	vis[0]=1;
	while(!q.empty())
	{
		State u=q.front();
		q.pop();
		if(u.state==((1<<m)-1))	return u.step;
		for(int i=0;i<m;i++)
		{
			tmp=u;
			tmp.state|=((cli1<<i)&((1<<m)-1));
			if(vis[tmp.state]==0)
			{
				tmp.step++;
				vis[tmp.state]=1;
				q.push(tmp);
			}
			tmp=u;
			tmp.state|=((cli2<<i)&((1<<m)-1));
			if(vis[tmp.state]==0)
			{
				tmp.step++;
				vis[tmp.state]=1;
				q.push(tmp);
			}	
		}
		for(int i=0;i<n;i++)
		{
			tmp=u;
			tmp.state|=((cli1>>i)&((1<<m)-1));
			if(vis[tmp.state]==0)
			{
				tmp.step++;
				vis[tmp.state]=1;
				q.push(tmp);
			}
			tmp=u;
			tmp.state|=((cli2>>i)&((1<<m)-1));
			if(vis[tmp.state]==0)
			{
				tmp.step++;
				vis[tmp.state]=1;
				q.push(tmp);
			}
		}
	}
}
int main()
{
	char str[100];
	while(cin>>n)
	{
		cin>>str;
		cli1=cli2=0;
		for(int i=0;i<n;i++)
		{
			if(str[i]=='*')
			{
				cli1|=1<<i;
				cli2|=1<<(n-i-1);
			}
		}
		cin>>m;
		if(cli1==0)
			cout<<-1<<endl;
		else
			cout<<bfs()<<endl;
	}
	return 0;
}