POJ 2488 -- A Knight's Journey(骑士游历)

 1 #include<iostream>
 2 #include<cstring>
 3 using namespace std;
 4 int r,c;///行r，列c
 5 
 6 const int dr[] = {-1, 1,-2, 2,-2,2,-1,1};
 7 const int dc[] = {-2,-2,-1,-1, 1,1, 2,2};
 8 bool chess[27][‘Z‘+1];
 9 
10 struct square{
11 int row;
12 char col;
13 };
14 
15 bool inside(int x,int y)
16 {
17     return x>=1 && x<=r && y>=‘A‘ && y<=‘A‘+c-1;
18 }
19 
20 bool dfs(square *way,int i,int j,int step)
21 {
22     chess[i][j]=true;
23     way[step].row=i;
24     way[step].col=j;
25     if(step==r*c)
26         return true;
27 
28     for(int k=0;k<8;k++)   //骑士从当前位置尝试跳到其他位置
29     {
30         int ii,jj;
31         ii = i+dr[k];jj = j+dc[k];
32         if(!chess[ii][jj] && inside(ii,jj))
33             if(dfs(way,ii,jj,step+1))
34                 return true;
35     }
36 
37     chess[i][j]=false;  //能执行到这步，说明前面跳的8步都不符合要求
38     return false;       //即当前位置是错误位置，擦除记录返回上一步
39 }
40 
41 int main()
42 {
43     int n;
44     cin>>n;
45     for(int i=1;i<=n;i++)
46     {
47         cin>>r>>c;
48         bool flag = false;
49         memset(chess,false,sizeof(chess));
50         square *way = new square[r*c+1];
51         for(int i=‘A‘;i<=‘A‘+c-1;i++)
52         {
53             for(int j=1;j<=r;j++)
54             {
55                 flag = dfs(way,j,i,1);
56                 if(flag)
57                     break;
58             }
59             if(flag)
60                     break;
61         }
62 
63         ///打印解
64         cout<<"Scenario #"<<i<<":"<<endl;
65         if(flag)
66         {
67             for(int k=1;k<=r*c;k++)
68                         cout<<way[k].col<<way[k].row;
69                     cout<<endl<<endl;
70         }else{
71             cout<<"impossible"<<endl<<endl;
72         }
73 
74     }
75     return 0;
76 }