poj 3083

刚开始提交的时候，超时，以为是stl queue的原因，把queue改成数组，结果还是超时，一直再找原因，后来将普通递归(非尾递归)改成尾递归的形式，就AC 了。

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1. #include <iostream>
   
2. #include <stdio.h>
   
3. #include<cstring>
   
4. #include<queue>
   
5. 
   
6. using namespace std;
   
7. 
   
8. struct move{
   
9.     int i;
   
10.     int j;
    
11. }MOVE[4] = {{-1,0} , {0,1},{1,0},{0,-1}};
    
12. 
    
13. int n,p,q,step;
    
14. int si,sj,ei,ej;
    
15. #define MAX_V (40+1)
    
16. 
    
17. char T[MAX_V][MAX_V];
    
18. char C[MAX_V][MAX_V];
    
19. 
    
20. int isValid(int i,int j)
    
21. {
    
22.     if ( i< 1 || i> q)
    
23.         return 0;
    
24.     if( j< 1 || j> p)
    
25.         return 0;
    
26. 
    
27.     return 1;
    
28. }
    
29. 
    
30. struct qv
    
31. {
    
32.     int i;
    
33.     int j;
    
34.     int l;
    
35. }PT[500000];
    
36. 
    
37. 
    
38. 
    
39. int bfs()
    
40. {
    
41.     memset(C,0,sizeof(C));
    
42.     int h=0;
    
43.     int t=1;
    
44. 
    
45.     PT[h].i=si;
    
46.     PT[h].j=sj;
    
47.     PT[h].l=1;
    
48. 
    
49.     while(h < t)
    
50.     {
    
51.         struct qv pt = PT[h];
    
52.         h++;
    
53. 
    
54.         //cout<<"h:"<<h<<endl;
    
55.         for(int m=0;m<4;m++)
    
56.         {
    
57.                 
    
58.             int mi = pt.i + MOVE[m].i;
    
59.             int mj = pt.j + MOVE[m].j;
    
60.             
    
61.             if( !isValid(mi,mj))
    
62.                 continue;
    
63. 
    
64.             if(C[mi][mj] != 0)
    
65.                 continue;
    
66.             if(T[mi][mj] == 'E')
    
67.                 return pt.l +1;
    
68.             
    
69.             if(T[mi][mj] == '.')
    
70.             {
    
71.                 PT[t].i = mi;
    
72.                 PT[t].j = mj;
    
73.                 PT[t].l = pt.l +1;
    
74.                 C[mi][mj]=1;
    
75. 
    
76.                 t++;
    
77.             }
    
78.         }    
    
79.     }
    
80. 
    
81.     return 0;
    
82. }
    
83. 
    
84. int dfsVisit(int i,int j,int rfirst,int d) //d代表方向，从哪个方向来的 rfirst代表右优先，还是左优先
    
85. {
    
86.     int start,mm,mi,mj;
    
87. 
    
88.     if(T[i][j] == 'E')
    
89.         return 1;
    
90. 
    
91.     if(!rfirst)
    
92.         start = d-1;
    
93.     else
    
94.         start = d+1;
    
95. 
    
96.     for( int c=0;c< 4;c++)
    
97.     {
    
98.         if(!rfirst)
    
99.             mm = start +c;
    
100.         else
     
101.             mm=start -c;
     
102. 
     
103. 
     
104.         //printf("before mm=%d \n",mm);
     
105.         if(mm < 0)
     
106.             mm += 4;
     
107. 
     
108.         if(mm > 3)
     
109.             mm -= 4;
     
110.         
     
111.         mi = i + MOVE[mm].i;
     
112.         mj = j + MOVE[mm].j;
     
113. 
     
114.         //printf("after mm=%d (%d,%d)->(%d,%d)\n",mm,i,j,mi,mj);
     
115. 
     
116.         //printf("\tm=%d mm=%d,mi=%d,mj=%d\n",m,mm,mi,mj);
     
117.         if ( !isValid(mi,mj) )
     
118.         {
     
119.             //printf("mi=%d mj=%d non valid\n",mi,mj);
     
120.             continue;
     
121.         }
     
122. 
     
123.         if( T[mi][mj] == '#' )
     
124.         {
     
125.             continue;
     
126.         }
     
127. 
     
128.         break;
     
129.     }
     
130. 
     
131.     
     
132.     return dfsVisit(mi,mj,rfirst,mm)+1;
     
133. }
     
134. 
     
135. int main()
     
136. {
     
137.     cin>>n;
     
138. 
     
139.     for(int k=1;k<=n;k++)
     
140.     {
     
141.         cin>>p>>q;
     
142.         for(int i=1;i<=q;i++)
     
143.         {
     
144.             for(int j=1;j<=p;j++)
     
145.             {
     
146.                 cin>>T[i][j];
     
147.                 if(T[i][j] == 'S')
     
148.                 {
     
149.                     si=i;
     
150.                     sj=j;
     
151.                 }
     
152.                 else if (T[i][j] == 'E')
     
153.                 {
     
154.                     ei=i;
     
155.                     ej=j;
     
156.                 }
     
157.             }
     
158.         }
     
159.         //cout<<"si:"<<si<<"sj:"<<sj<<endl;
     
160.         //cout<<"ei:"<<ei<<"ej:"<<ej<<endl;
     
161. 
     
162.         
     
163.         step=1;
     
164.         memset(C,0,sizeof(C));
     
165.         step=dfsVisit(si,sj,0,0);
     
166.         cout<<step<<" ";
     
167. 
     
168.         step=1;
     
169.         memset(C,0,sizeof(C));
     
170.         step=dfsVisit(si,sj,1,0);
     
171.         cout<<step<<" ";
     
172.         
     
173.         step=bfs();
     
174.         cout<<step;
     
175.         cout<<endl;
     
176.         
     
177.     }
     
178. }