poj 2488

字典序 x 1-7 y A-B
 {-1,-2},{1,-2},{-2,-1},{2,-1},{-2,1},{2,1},{-1,2},{1,2}

深度搜索如果避免存在回边的情况，即马要不重复的走过所有格。

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1. #include <iostream>
   
2. #include <list>
   
3. #include <cstring>
   
4. 
   
5. using namespace std;
   
6. 
   
7. 
   
8. #define MAX_V (26+1)
   
9. char board[MAX_V][MAX_V];
   
10. int p,q,n;
    
11. 
    
12. struct move
    
13. {
    
14.     int i;
    
15.     int j;
    
16. //}MOVE[8]={{1,-2},{-1,-2},{2,-1},{-2,-1},{2,1},{-2,1},{1,2},{-1,2}};
    
17. //}MOVE[8]={{-1,-2},{1,-2},{-2,-1},{2,-1},{-2,1},{2,1},{-1,2},{1,2},};
    
18. //}MOVE[8]={{2,-1},{1,-2},{1,-2},{2,-1},{2,1},{1,2},{-1,2},{-2,1}};
    
19. //}MOVE[8]={{-2,-1},{-2,1},{-1,-2},{-1,2},{1,-2},{1,2},{2,-1},{2,1}};
    
20. }MOVE[8]={ {-1,-2},{1,-2},{-2,-1},{2,-1},{-2,1},{2,1},{-1,2},{1,2}};
    
21. //}MOVE[8]={{-2,-1},{-2,1},{-1,-2},{-1,2},{1,-2},{1,2},{2,-1},{2,1}};
    
22. 
    
23. struct qv
    
24. {
    
25.     int i;
    
26.     int j;
    
27. };
    
28. 
    
29. 
    
30. list<struct qv> dfsList;
    
31. 
    
32. int is_valid(int i,int j)
    
33. {
    
34.     if(i < 1 || i> p)
    
35.         return 0;
    
36.     if(j< 1 || j> q)
    
37.         return 0;
    
38. 
    
39.     return 1;
    
40. }
    
41. int dfsVisit(int i,int j)
    
42. {
    
43.     
    
44.     board[i][j]=1;    
    
45.     struct qv _qv = {i,j};
    
46.     dfsList.push_back(_qv);
    
47. 
    
48.     if(dfsList.size() == p*q)
    
49.         return 1;
    
50. 
    
51.     for(int m=0;m<8;m++)
    
52.     {
    
53.         int mi=MOVE[m].i +i;
    
54.         int mj = MOVE[m].j +j;
    
55. 
    
56.         if(!is_valid(mi,mj))
    
57.             continue;
    
58.         if(board[mi][mj] == 0)
    
59.         {
    
60.             if(dfsVisit(mi,mj))
    
61.             {
    
62.                 return 1;
    
63.             }
    
64.         }
    
65.     }
    
66. 
    
67.     board[i][j]=0;
    
68.     dfsList.pop_back();
    
69.     return 0;
    
70. }
    
71. 
    
72. int dfs()
    
73. {
    
74.         for(int i=1;i<=p;i++)
    
75.         {
    
76.             for(int j=1;j<=q;j++)
    
77.             {
    
78.                 memset(board,0,sizeof(board));
    
79.                 dfsList.erase(dfsList.begin(),dfsList.end());
    
80.                 //try start with i,j
    
81.                 dfsVisit(i,j);    
    
82.                 //cout<<"after dfs i:"<<i<<"j:"<<j<<"size:"<<dfsList.size()<<endl;
    
83. 
    
84.                 if(dfsList.size() == p*q)
    
85.                 {
    
86.                     return 1;
    
87.                 }
    
88.             }
    
89.         }
    
90. 
    
91.         return 0;
    
92. }
    
93. 
    
94. int index_v=1;
    
95. int main()
    
96. {
    
97.     cin >> n;
    
98.     for(int k=1;k<=n;k++)
    
99.     {
    
100.         cin >>p>>q;
     
101.         //cout<<"p:"<<p<<"q:"<<q<<endl;
     
102. 
     
103.         cout<<"Scenario #"<<index_v<<":"<<endl;
     
104.         if(dfs())
     
105.         {
     
106.             for(list<struct qv>::iterator lIter = dfsList.begin();
     
107.                     lIter != dfsList.end();
     
108.                     ++lIter)
     
109.             {
     
110.                 struct qv _qv = (*lIter);
     
111.                 cout<<(char)(_qv.j+'A'-1)<<_qv.i;
     
112.             }
     
113.             cout<<endl;
     
114.         }
     
115.         else
     
116.         {
     
117.             cout<<"impossible"<<endl;
     
118.         }
     
119.         cout<<endl;
     
120. 
     
121.         index_v++;
     
122.     }
     
123. }