dfs：马踏棋盘

  1 #include<stdio.h>
  2 #include<time.h>
  3 
  4 #define X 8
  5 #define Y 8
  6 
  7 int chess[X][Y];
  8 
  9 //查找当前位置的下一个位置
 10 int nextxy(int* x, int* y, int count)
 11 {
 12     switch (count)
 13     {
 14     case 0:
 15         if (*x + 2 <= X - 1 && *y - 1 >= 0 && chess[*x + 2][*y - 1] == 0)
 16         {
 17             *x += 2;
 18             *y -= 1;
 19             return 1;
 20         }
 21         break;
 22 
 23     case 1:
 24         if (*x + 2 <= X - 1 && *y + 1 <= Y - 1 && chess[*x + 2][*y + 1] == 0)
 25         {
 26             *x += 2;
 27             *y += 1;
 28             return 1;
 29         }
 30         break;
 31 
 32     case 2:
 33         if (*x + 1 <= X - 1 && *y + 2 <= Y - 1 && chess[*x + 1][*y + 2] == 0)
 34         {
 35             *x += 1;
 36             *y += 2;
 37             return 1;
 38         }
 39         break;
 40 
 41     case 3:
 42         if (*x - 1 >= 0 && *y + 2 <= Y - 1 && chess[*x - 1][*y + 2] == 0)
 43         {
 44             *x -= 1;
 45             *y += 2;
 46             return 1;
 47         }
 48         break;
 49         
 50     case 4:
 51         if (*x - 2 >= 0 && *y + 1 <= Y - 1 && chess[*x - 2][*y + 1] == 0)
 52         {
 53             *x -= 2;
 54             *y += 1;
 55             return 1;
 56         }
 57         break;
 58 
 59     case 5:
 60         if (*x - 2 >= 0 && *y - 1 >= 0 && chess[*x - 2][*y - 1] == 0)
 61         {
 62             *x -= 2;
 63             *y -= 1;
 64             return 1;
 65         }
 66         break;
 67         
 68     case 6:
 69         if (*x - 1 >= 0 && *y - 2 >= 0 && chess[*x - 1][*y - 2] == 0)
 70         {
 71             *x -= 1;
 72             *y -= 2;
 73             return 1;
 74         }
 75         break;
 76 
 77     case 7:
 78         if (*x + 1 <= X - 1 && *y - 2 >= 0 && chess[*x + 1][*y - 2] == 0)
 79         {
 80             *x += 1;
 81             *y -= 2;
 82             return 1;
 83         }
 84         break;
 85     default:
 86         break;
 87     }
 88 
 89     return 0;
 90 }
 91 
 92 void print()
 93 {
 94     int i, j;
 95     for (i = 0; i < X; i++)
 96     {
 97         for (j = 0; j < Y; j++)
 98         {
 99             printf("%2d\t", chess[i][j]);
100         }
101         printf("\n");
102     }
103 
104     printf("\n");
105 }
106 
107 //深度优先遍历
108 //(x,y)为位置坐标
109 //tag为标记变量，每走一步，tag+1
110 int TravelChessBoard(int x, int y, int tag)
111 {
112     int x1 = x;
113     int y1 = y;
114     int flag = 0;
115     int count = 1;
116     chess[x][y] = tag;
117 
118     if (tag == X * Y)
119     {
120         //打印棋盘
121         print();
122         return 1;
123     }
124     //找到马的下一个可走坐标（x1，y1），如果找到flag = 1，否则为0
125     flag = nextxy(&x1, &y1, count);
126     while (flag == 0 && count < 8)
127     {
128         count++;
129         flag = nextxy(&x1, &y1, count);
130     }
131 
132 
133     while (flag)
134     {
135         if (TravelChessBoard(x1, y1, tag + 1))
136         {
137             return 1;
138         }
139 
140         //继续找到马的下一步的可走的坐标（x1，y1），如果找到flag = 1，否则为0
141         x1 = x;
142         y1 = y;
143         count++;
144 
145         flag = nextxy(&x1, &y1, count);
146         while (flag == 0 && count < 8)
147         {
148             count++;
149             flag = nextxy(&x1, &y1, count);
150         }
151     }
152 
153     if (flag == 0)
154     {
155         chess[x][y] = 0;
156     }
157 
158     return 0;
159 }
160 
161 int main()
162 {
163     int i, j;
164     clock_t start, finish;
165 
166     start = clock();
167 
168     for (i = 0; i < X; i++)
169     {
170         for (j = 0; j < Y; j++)
171         {
172             chess[i][j] = 0;
173         }
174     }
175 
176     printf("下面开始马踏棋盘：\n");
177     if (!TravelChessBoard(1, 0, 1))
178     {
179         printf("马踏棋盘失败了\n");
180     }
181 
182     finish = clock();
183     printf("\n本次计算义工耗时：%f\n\n", (double)(finish - start) / CLOCKS_PER_SEC);
184 
185     return 0;
186 }