C#递归求解八皇后
很久没更新Blog了,开始玩玩算法吧,用递归写了一下八皇后,不知道是不是最优方案,继续研究其他的解法,尝试下回朔,代码如下
using
System;
using
System.Collections.Generic;
using
System.Text;
namespace
Queen
{
/*
* 八皇后问题
* @Author: Red_angelX
*/
class Program
{
const int NCOUNT = 8;
static int[] QueenMap = new int[NCOUNT];
static int iCount = 1;
static void Main(string[] args)
{
int current = System.Environment.TickCount;
PlayQueen(0);
Console.WriteLine("Eclped {0} ms", Environment.TickCount - current);
Console.Read();
}
/*
* 核心函数,放置第N枚皇后(递归)
*/
static void PlayQueen(int n)
{
if (n == NCOUNT)
{
PrintResult();
return;
}
for (int i = 1; i <= NCOUNT; i++)
{
QueenMap[n] = i;
if (IsValid(n))
PlayQueen(n+1);
}
}
/*
* 输出结果
*/
static void PrintResult()
{
Console.Write("No.{0} ", iCount++);
for (int i = 0; i < NCOUNT; i++)
Console.Write("{0} ", QueenMap[i]);
Console.Write(" ");
}
/*
* 检查第n个皇后放上去之后是否合法
*/
static bool IsValid(int n)
{
for (int i = 0; i < n; i++)
{
if (QueenMap[i] == QueenMap[n])
return false;
if (Math.Abs(QueenMap[i] - QueenMap[n]) == n - i)
return false;
}
return true;
}
}
}
执行结果(Release版本):
No.
1
1
5
8
6
3
7
2
4
No.
2
1
6
8
3
7
4
2
5
No.
3
1
7
4
6
8
2
5
3
No.
4
1
7
5
8
2
4
6
3
No.
5
2
4
6
8
3
1
7
5
No.
6
2
5
7
1
3
8
6
4
No.
7
2
5
7
4
1
8
6
3
No.
8
2
6
1
7
4
8
3
5
No.
9
2
6
8
3
1
4
7
5
No.
10
2
7
3
6
8
5
1
4
No.
11
2
7
5
8
1
4
6
3
No.
12
2
8
6
1
3
5
7
4
No.
13
3
1
7
5
8
2
4
6
No.
14
3
5
2
8
1
7
4
6
No.
15
3
5
2
8
6
4
7
1
No.
16
3
5
7
1
4
2
8
6
No.
17
3
5
8
4
1
7
2
6
No.
18
3
6
2
5
8
1
7
4
No.
19
3
6
2
7
1
4
8
5
No.
20
3
6
2
7
5
1
8
4
No.
21
3
6
4
1
8
5
7
2
No.
22
3
6
4
2
8
5
7
1
No.
23
3
6
8
1
4
7
5
2
No.
24
3
6
8
1
5
7
2
4
No.
25
3
6
8
2
4
1
7
5
No.
26
3
7
2
8
5
1
4
6
No.
27
3
7
2
8
6
4
1
5
No.
28
3
8
4
7
1
6
2
5
No.
29
4
1
5
8
2
7
3
6
No.
30
4
1
5
8
6
3
7
2
No.
31
4
2
5
8
6
1
3
7
No.
32
4
2
7
3
6
8
1
5
No.
33
4
2
7
3
6
8
5
1
No.
34
4
2
7
5
1
8
6
3
No.
35
4
2
8
5
7
1
3
6
No.
36
4
2
8
6
1
3
5
7
No.
37
4
6
1
5
2
8
3
7
No.
38
4
6
8
2
7
1
3
5
No.
39
4
6
8
3
1
7
5
2
No.
40
4
7
1
8
5
2
6
3
No.
41
4
7
3
8
2
5
1
6
No.
42
4
7
5
2
6
1
3
8
No.
43
4
7
5
3
1
6
8
2
No.
44
4
8
1
3
6
2
7
5
No.
45
4
8
1
5
7
2
6
3
No.
46
4
8
5
3
1
7
2
6
No.
47
5
1
4
6
8
2
7
3
No.
48
5
1
8
4
2
7
3
6
No.
49
5
1
8
6
3
7
2
4
No.
50
5
2
4
6
8
3
1
7
No.
51
5
2
4
7
3
8
6
1
No.
52
5
2
6
1
7
4
8
3
No.
53
5
2
8
1
4
7
3
6
No.
54
5
3
1
6
8
2
4
7
No.
55
5
3
1
7
2
8
6
4
No.
56
5
3
8
4
7
1
6
2
No.
57
5
7
1
3
8
6
4
2
No.
58
5
7
1
4
2
8
6
3
No.
59
5
7
2
4
8
1
3
6
No.
60
5
7
2
6
3
1
4
8
No.
61
5
7
2
6
3
1
8
4
No.
62
5
7
4
1
3
8
6
2
No.
63
5
8
4
1
3
6
2
7
No.
64
5
8
4
1
7
2
6
3
No.
65
6
1
5
2
8
3
7
4
No.
66
6
2
7
1
3
5
8
4
No.
67
6
2
7
1
4
8
5
3
No.
68
6
3
1
7
5
8
2
4
No.
69
6
3
1
8
4
2
7
5
No.
70
6
3
1
8
5
2
4
7
No.
71
6
3
5
7
1
4
2
8
No.
72
6
3
5
8
1
4
2
7
No.
73
6
3
7
2
4
8
1
5
No.
74
6
3
7
2
8
5
1
4
No.
75
6
3
7
4
1
8
2
5
No.
76
6
4
1
5
8
2
7
3
No.
77
6
4
2
8
5
7
1
3
No.
78
6
4
7
1
3
5
2
8
No.
79
6
4
7
1
8
2
5
3
No.
80
6
8
2
4
1
7
5
3
No.
81
7
1
3
8
6
4
2
5
No.
82
7
2
4
1
8
5
3
6
No.
83
7
2
6
3
1
4
8
5
No.
84
7
3
1
6
8
5
2
4
No.
85
7
3
8
2
5
1
6
4
No.
86
7
4
2
5
8
1
3
6
No.
87
7
4
2
8
6
1
3
5
No.
88
7
5
3
1
6
8
2
4
No.
89
8
2
4
1
7
5
3
6
No.
90
8
2
5
3
1
7
4
6
No.
91
8
3
1
6
2
5
7
4
No.
92
8
4
1
3
6
2
7
5
Eclped
94
ms
using
System;
using
System.Collections.Generic;
using
System.Text;
namespace
Queen
{
/*
* 八皇后问题 * @Author: Red_angelX */ class Program { const int NCOUNT = 8; static int[] QueenMap = new int[NCOUNT]; static int iCount = 1; static void Main(string[] args) { int current = System.Environment.TickCount; PlayQueen(0); Console.WriteLine("Eclped {0} ms", Environment.TickCount - current); Console.Read(); } /* * 核心函数,放置第N枚皇后(递归) */ static void PlayQueen(int n) { if (n == NCOUNT) { PrintResult(); return; } for (int i = 1; i <= NCOUNT; i++) { QueenMap[n] = i; if (IsValid(n)) PlayQueen(n+1); } } /* * 输出结果 */ static void PrintResult() { Console.Write("No.{0} ", iCount++); for (int i = 0; i < NCOUNT; i++) Console.Write("{0} ", QueenMap[i]); Console.Write(" "); } /* * 检查第n个皇后放上去之后是否合法 */ static bool IsValid(int n) { for (int i = 0; i < n; i++) { if (QueenMap[i] == QueenMap[n]) return false; if (Math.Abs(QueenMap[i] - QueenMap[n]) == n - i) return false; } return true; } }}
执行结果(Release版本):
No.
1
1
5
8
6
3
7
2
4
No.
2
1
6
8
3
7
4
2
5
No.
3
1
7
4
6
8
2
5
3
No.
4
1
7
5
8
2
4
6
3
No.
5
2
4
6
8
3
1
7
5
No.
6
2
5
7
1
3
8
6
4
No.
7
2
5
7
4
1
8
6
3
No.
8
2
6
1
7
4
8
3
5
No.
9
2
6
8
3
1
4
7
5
No.
10
2
7
3
6
8
5
1
4
No.
11
2
7
5
8
1
4
6
3
No.
12
2
8
6
1
3
5
7
4
No.
13
3
1
7
5
8
2
4
6
No.
14
3
5
2
8
1
7
4
6
No.
15
3
5
2
8
6
4
7
1
No.
16
3
5
7
1
4
2
8
6
No.
17
3
5
8
4
1
7
2
6
No.
18
3
6
2
5
8
1
7
4
No.
19
3
6
2
7
1
4
8
5
No.
20
3
6
2
7
5
1
8
4
No.
21
3
6
4
1
8
5
7
2
No.
22
3
6
4
2
8
5
7
1
No.
23
3
6
8
1
4
7
5
2
No.
24
3
6
8
1
5
7
2
4
No.
25
3
6
8
2
4
1
7
5
No.
26
3
7
2
8
5
1
4
6
No.
27
3
7
2
8
6
4
1
5
No.
28
3
8
4
7
1
6
2
5
No.
29
4
1
5
8
2
7
3
6
No.
30
4
1
5
8
6
3
7
2
No.
31
4
2
5
8
6
1
3
7
No.
32
4
2
7
3
6
8
1
5
No.
33
4
2
7
3
6
8
5
1
No.
34
4
2
7
5
1
8
6
3
No.
35
4
2
8
5
7
1
3
6
No.
36
4
2
8
6
1
3
5
7
No.
37
4
6
1
5
2
8
3
7
No.
38
4
6
8
2
7
1
3
5
No.
39
4
6
8
3
1
7
5
2
No.
40
4
7
1
8
5
2
6
3
No.
41
4
7
3
8
2
5
1
6
No.
42
4
7
5
2
6
1
3
8
No.
43
4
7
5
3
1
6
8
2
No.
44
4
8
1
3
6
2
7
5
No.
45
4
8
1
5
7
2
6
3
No.
46
4
8
5
3
1
7
2
6
No.
47
5
1
4
6
8
2
7
3
No.
48
5
1
8
4
2
7
3
6
No.
49
5
1
8
6
3
7
2
4
No.
50
5
2
4
6
8
3
1
7
No.
51
5
2
4
7
3
8
6
1
No.
52
5
2
6
1
7
4
8
3
No.
53
5
2
8
1
4
7
3
6
No.
54
5
3
1
6
8
2
4
7
No.
55
5
3
1
7
2
8
6
4
No.
56
5
3
8
4
7
1
6
2
No.
57
5
7
1
3
8
6
4
2
No.
58
5
7
1
4
2
8
6
3
No.
59
5
7
2
4
8
1
3
6
No.
60
5
7
2
6
3
1
4
8
No.
61
5
7
2
6
3
1
8
4
No.
62
5
7
4
1
3
8
6
2
No.
63
5
8
4
1
3
6
2
7
No.
64
5
8
4
1
7
2
6
3
No.
65
6
1
5
2
8
3
7
4
No.
66
6
2
7
1
3
5
8
4
No.
67
6
2
7
1
4
8
5
3
No.
68
6
3
1
7
5
8
2
4
No.
69
6
3
1
8
4
2
7
5
No.
70
6
3
1
8
5
2
4
7
No.
71
6
3
5
7
1
4
2
8
No.
72
6
3
5
8
1
4
2
7
No.
73
6
3
7
2
4
8
1
5
No.
74
6
3
7
2
8
5
1
4
No.
75
6
3
7
4
1
8
2
5
No.
76
6
4
1
5
8
2
7
3
No.
77
6
4
2
8
5
7
1
3
No.
78
6
4
7
1
3
5
2
8
No.
79
6
4
7
1
8
2
5
3
No.
80
6
8
2
4
1
7
5
3
No.
81
7
1
3
8
6
4
2
5
No.
82
7
2
4
1
8
5
3
6
No.
83
7
2
6
3
1
4
8
5
No.
84
7
3
1
6
8
5
2
4
No.
85
7
3
8
2
5
1
6
4
No.
86
7
4
2
5
8
1
3
6
No.
87
7
4
2
8
6
1
3
5
No.
88
7
5
3
1
6
8
2
4
No.
89
8
2
4
1
7
5
3
6
No.
90
8
2
5
3
1
7
4
6
No.
91
8
3
1
6
2
5
7
4
No.
92
8
4
1
3
6
2
7
5
Eclped
94
ms