hdu 4634 Swipe Bo（bfs 状态压缩）

来源：互联网发布：淘宝第二层级流量比例编辑：程序博客网时间：2024/05/04 17:34

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_JUDGEfreopen("in.txt", "r", stdin);#endifwhile (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;}

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