洛谷1126-BFS

题目链接 https://www.luogu.org/problemnew/show/P1126

 1 #include<iostream>
 2 #include<cstring>
 3 #include<queue>
 4 using namespace std;
 5 bool map[51][51];
 6 int vis[51][51][5];
 7 struct node{
 8     int x,y,dir,step;
 9 };
10 queue<node> q;
11 node aaa;
12 int tx,ty,f,st,x1,x2,y1,y2,n,m;
13 int fx[4]={0,1,0,-1},fy[4]={1,0,-1,0};
14 void bfs()
15 {
16     while(!q.empty()){
17         aaa=q.front();
18         q.pop();
19         tx=aaa.x;
20         ty=aaa.y;
21         if(tx==x2&&ty==y2){
22             cout<<aaa.step;
23             return;
24         }
25         for(int j=1;j<=3;j++){
26             tx+=fx[aaa.dir];
27             ty+=fy[aaa.dir];
28         if(tx<=0||ty<=0||tx>=n||ty>=m||map[tx][ty]==1)
29             break;
30         else if(!vis[tx][ty][aaa.dir]){
31             vis[tx][ty][aaa.dir]=true;
32             node cnew;
33             cnew.x=tx;
34             cnew.y=ty;
35             cnew.dir=aaa.dir;
36             cnew.step=aaa.step+1;
37             q.push(cnew);
38         }
39         }
40     node cnew;
41     cnew.x=aaa.x;
42     cnew.y=aaa.y;
43     cnew.step=aaa.step+1;
44     cnew.dir=aaa.dir-1;
45     if(cnew.dir==-1) cnew.dir=3;//如果dir=-1的话，就相当于由东向北
46     if(!vis[cnew.x][cnew.y][cnew.dir]){
47         vis[cnew.x][cnew.y][cnew.dir]=true;
48         q.push(cnew);
49     }
50     cnew.dir=aaa.dir+1;
51     if(cnew.dir==4) cnew.dir=0;
52     if(!vis[cnew.x][cnew.y][cnew.dir]){
53         vis[cnew.x][cnew.y][cnew.dir]=true;
54         q.push(cnew);
55     }
56     }
57     cout<<"-1";
58 }
59 int main()
60 {
61     cin>>n>>m;
62     for(int i=1;i<=n;i++){
63         for(int j=1;j<=m;j++){
64             bool a;
65             cin>>a;
66             if(a){
67                 map[i][j]=1;
68                 map[i-1][j]=1;
69                 map[i-1][j-1]=1;
70                 map[i][j-1]=1;
71             }
72         }
73     }
74     for(int i=1;i<=n;i++){
75         map[n][i]=1;
76         map[i][m]=1;
77     }
78     char fang;
79     cin>>x1>>y1>>x2>>y2>>fang;
80     if(fang=='E') aaa.dir=0;
81     else if(fang=='S') aaa.dir=1;
82     else if(fang=='W') aaa.dir=2;
83     else aaa.dir=3;
84     aaa.x=x1;
85     aaa.y=y1;
86     q.push(aaa);
87     bfs();
88     return 0;
89 }