hdu 4634 Swipe Bo（bfs 状态压缩）

宽搜，根据K的个数判断状态，需要注意的一点是遇到转向点后转向不影响原来的步数

#include<cstdio>
#include<algorithm>
#pragma comment(linker, "/STACK:1024000000,1024000000")
using namespace std;
const int MAXN = 205;
const int MAXK = 130;
char vis[MAXN][MAXN][MAXK];
char mmp[MAXN][MAXN];
#define BORD '0'
#define NO '1'
#define YS '2'
const int dir[4][2] = {
	1,0, -1,0, 0,1, 0,-1
};
struct _state
{
	int x, y, k, stp;
	_state(int xx, int yy, int kk, int ss)
	{
		x = xx; y = yy; k = kk; stp = ss;
	}
	_state(){}
}q[MAXN*MAXN*MAXK];
int n, m, nkey, mxk, bg, ed;
int sx, sy, ex, ey, dkey[MAXN][MAXN];
int isfnd, res;
void m_search(_state st)
{
	int x, y;
	for (int i = 0; i< 4; ++i)
	{
		_state tp = st;
		int ax = dir[i][0], ay = dir[i][1];
		int flg = 1;
		while (flg)
		{
			x = tp.x+ax; y = tp.y+ay;
			if (vis[x][y][0] == BORD) break;		// 边界 
			switch (mmp[x][y])
			{
			case '#':
				if (vis[tp.x][tp.y][tp.k] == YS)
				{
					flg = 0;
					break;
				}
				vis[tp.x][tp.y][tp.k] = YS;
				if (tp.x!=st.x||tp.y!=st.y)
					q[ed++] = _state(tp.x, tp.y, tp.k, tp.stp+1);
				flg = 0;
				break;
			case 'E':
				if (tp.k == mxk)
				{
					res = tp.stp+1;
					isfnd = 1; flg = 0;
				}				
				break;
			case 'K':
				tp.k |= 1<<dkey[x][y];
				break;
			case 'U': 
				if (vis[x][y][tp.k]==YS)
				{
					flg = 0; break;
				}				
				ax = dir[1][0]; ay = dir[1][1]; 
				vis[x][y][tp.k] = YS; 
				break; 	
			case 'D': 
				if (vis[x][y][tp.k]==YS)
				{
					flg = 0; break;
				}
				ax = dir[0][0]; ay = dir[0][1]; 
				vis[x][y][tp.k] = YS; 
				break;
			case 'L': 
				if (vis[x][y][tp.k]==YS)
				{
					flg = 0; break;
				}
				ax = dir[3][0]; ay = dir[3][1]; 
				vis[x][y][tp.k] = YS; 
				break;
			case 'R': 
				if (vis[x][y][tp.k]==YS)
				{
					flg = 0; break;
				}
				ax = dir[2][0]; ay = dir[2][1]; 
				vis[x][y][tp.k] = YS; 
				break;
			}
			tp.x = x; tp.y = y; 
		}
	}
}
void bfs()
{
	mxk = (1<<nkey)-1;
	res = -1;
	bg = ed = 0;
	isfnd = 0;
	q[ed++] = _state(sx,sy,0,0);
	_state tp;
	while (bg<ed && !isfnd)
	{
		tp = q[bg++];
		m_search(tp);
	}
}
int main()
{
#ifndef ONLINE_JUDGE
	freopen("in.txt", "r", stdin);
#endif
	while (scanf("%d%d", &n, &m)!=EOF)
	{
		memset(vis, BORD, sizeof vis);
		nkey = 0;
		for (int i = 1; i<= n; ++i)
		{
			scanf("%s", mmp[i]+1);
			for (int j = 1; j<= m; ++j)
			{
				memset(vis[i][j], NO, MAXK);
				if (mmp[i][j] == 'S') sx=i,sy=j,mmp[i][j]='.';
				else if(mmp[i][j] == 'E') ex=i,ey=j;
				else if (mmp[i][j] == 'K')
				{
					dkey[i][j] = nkey++;
				}
			}
		}		
		bfs();	
		printf("%d\n", res);
	}
	return 0;
}