P1126-机器人搬重物

 1 #include <bits/stdc++.h>
 2 #define _for(i,a,b) for(int i = a;i < b;i ++)
 3 #define maxn 52
 4 #define INF 0x3f3f3f3f
 5 using namespace std;
 6 int m,n;
 7 int mp[maxn][maxn];
 8 int vis[maxn][maxn][4];
 9 int dx[] = {-1,0,1,0};
10 int dy[] = {0,-1,0,1};
11 struct P
12 {
13     int x;
14     int y;
15     int dr;
16 };
17 P st,ed;
18 
19 bool valid(P p)
20 {
21     if(p.x>0 && p.y>0 && p.x<m && p.y<n && mp[p.x][p.y]==0)
22         return true;
23     return false;
24 }
25 
26 int bfs()
27 {
28     queue<pair<P,int>> q;
29     q.push({st,0});
30     vis[st.x][st.y][st.dr] = 0;
31     while(!q.empty())
32     {
33         pair<P,int> nw = q.front();
34         q.pop();
35         P np = nw.first;
36         P tp;
37 
38         tp = np;
39         tp.dr = (np.dr+3)%4;
40         if(valid(tp) && nw.second+1<vis[tp.x][tp.y][tp.dr])
41         {
42             vis[tp.x][tp.y][tp.dr] = nw.second+1;
43             q.push({tp,nw.second+1});
44         }
45 
46         tp = np;
47         tp.dr = (np.dr+5)%4;
48         if(valid(tp) && nw.second+1<vis[tp.x][tp.y][tp.dr])
49         {
50             vis[tp.x][tp.y][tp.dr] = nw.second+1;
51             q.push({tp,nw.second+1});
52         }
53 
54         tp = np;
55         _for(i,0,3)
56         {
57             tp.x += dx[np.dr];
58             tp.y += dy[np.dr];
59             if(!valid(tp))
60                 break;
61             if(nw.second+1<vis[tp.x][tp.y][tp.dr])
62             {
63                 vis[tp.x][tp.y][tp.dr] = nw.second+1;
64                 q.push({tp,nw.second+1});
65             }
66         }
67     }
68     return min(vis[ed.x][ed.y][3],min(vis[ed.x][ed.y][2],min(vis[ed.x][ed.y][1],vis[ed.x][ed.y][0])));
69 }
70 int main()
71 {
72     memset(mp,0,sizeof(mp));
73     memset(vis,INF,sizeof(vis));
74     scanf("%d%d",&m,&n);
75     _for(i,0,m)
76     _for(j,0,n)
77     {
78         int tmp;
79         scanf("%d",&tmp);
80         if(tmp==1)
81             mp[i][j] = mp[i][j+1] = mp[i+1][j] = mp[i+1][j+1] = 1;
82     }
83     char c;
84     scanf("%d%d%d%d %c",&st.x,&st.y,&ed.x,&ed.y,&c);
85     if(c=='N') st.dr = 0;
86     else if(c=='W') st.dr = 1;
87     else if(c=='S') st.dr = 2;
88     else if(c=='E') st.dr = 3;
89     int rnt = bfs();
90     if(rnt != INF)
91         printf("%d\n",bfs());
92     else
93         printf("-1\n");
94     return 0;
95 }