HDU 1175 连连看【BFS】

 1 #include<iostream>  
 2 #include<cstdio>  
 3 #include<cstring> 
 4 #include <cmath> 
 5 #include<stack>
 6 #include<vector>
 7 #include<map> 
 8 #include<set>
 9 #include<queue> 
10 #include<algorithm>  
11 using namespace std;
12 
13 typedef long long LL;
14 const int INF = (1<<30)-1;
15 const int mod=1000000007;
16 const int maxn=1000005;
17 
18 int g[1005][1005];
19 int turn[1005][1005];
20 int n,m;
21 int dir[4][2]={1,0,-1,0,0,1,0,-1};
22 
23 struct node{
24     int x,y;
25     int turn;
26     int dir;
27 };
28 
29 node st,en;
30 
31 void bfs(){
32     queue<node> q;
33     node u;
34     u.x=st.x;u.y=st.y;u.turn=0;u.dir=-5;
35     turn[u.x][u.y]=0;
36     q.push(u);
37     
38     while(!q.empty()){
39         u=q.front();q.pop();
40         
41         node v;
42         for(int i=0;i<4;i++){
43             v.x=u.x+dir[i][0];
44             v.y=u.y+dir[i][1];
45             v.turn=u.turn;
46             v.dir=u.dir;
47             
48             if(u.x==en.x&&u.y==en.y&&u.turn<=2){
49                 printf("YES\n");
50                 return;
51             }
52             if(v.dir!=i&&v.dir!=-5) v.turn++;
53             
54             if(v.x==en.x&&v.y==en.y&&v.turn<=2){
55                 printf("YES\n");
56                 return;
57             }
58             
59             if(v.x<1||v.x>n||v.y<1||v.y>m||g[v.x][v.y]!=0) continue;
60                     
61             if(v.turn>2) continue;
62         
63             if(v.turn<=turn[v.x][v.y]){
64                 turn[v.x][v.y]=v.turn;
65                 v.dir=i;
66                 q.push(v);
67             }        
68         }    
69     }
70     printf("NO\n");
71 }
72 
73 int main(){
74     while(scanf("%d %d",&n,&m)!=EOF&&n&&m){
75         for(int i=1;i<=n;i++){
76             for(int j=1;j<=m;j++) cin>>g[i][j];
77         }
78         
79         int q;
80         scanf("%d",&q);
81         while(q--){
82             for(int i=1;i<=n;i++)
83              for(int j=1;j<=m;j++) turn[i][j]=1000000;
84             scanf("%d %d %d %d",&st.x,&st.y,&en.x,&en.y);
85             
86             if(g[st.x][st.y]!=g[en.x][en.y]||!g[st.x][st.y]||!g[en.x][en.y]) printf("NO\n");
87             else bfs();
88         }    
89     }
90     return 0;
91 }