這是之前我寫的原始的 VB.NET 版本：
http://www.cnblogs.com/RChen/archive/2010/05/17/1737587.html
轉化為 C# 版本後，還進行了一些重構。包括修改成了強型別，以及使用了 Parallel.ForEach，但是發現沒有收到預期的效果。效能提升比較少。
研究後發現，其實問題的關鍵在於要通過某種方式對遍歷的可能性進行剪枝，這樣才能減少遍歷次數，從而提升效能。而且，由於結果是通過 yield return 和 IEnumerable 實現的，並沒有實現 IList 或者 Array. 所以它本質上並不支援按索引範圍拆分的 Parallel.ForEach 工作方式，而實際估計是使用的幾個 chunk 輪番讀取的低效方式，這樣在各個 chunk 之間就有執行緒同步的開銷，如前文所說。這個效能優化只好留待後面有空再繼續研究。
下面是目前的狀況的實現程式碼：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Collections;
namespace NonDeterministicEngineCS
{
class Program
{
static void Main(string[] args)
{
Benchmarking(new Action(Test1), "Test1() 執行完成，花費：{0}毫秒。");
Console.WriteLine("====================================================");
Benchmarking(new Action(Test2), "Test2() 執行完成，花費：{0}毫秒。");
Console.WriteLine("====================================================");
Benchmarking(new Action(Test3), "Test3() 執行完成，花費：{0}毫秒。");
Console.ReadLine();
}
// 一個簡單的測試例子
public static void Test1()
{
NonDeterministicEngine engine = new NonDeterministicEngine();
engine.AddParam("a", new int[] { 1, 2, 3, 4, 5, 6 });
engine.AddParam("b", new int[] { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 });
engine.AddRequire((int a) => a > 2 && a < 9);
engine.AddRequire((int b) => b > 5 && b <= 10);
engine.AddRequire((int a, int b) => a == b - 1);
engine.EachResult(
result => Console.WriteLine("a = {0}, b = {1}", result["a"], result["b"]));
}
// 愛因斯坦謎題
public static void Test2()
{
NonDeterministicEngine engine = new NonDeterministicEngine();
engine.AddParam("baker", new int[] { 1, 2, 3, 4, 5 });
engine.AddParam("cooper", new int[] { 1, 2, 3, 4, 5 });
engine.AddParam("fletcher", new int[] { 1, 2, 3, 4, 5 });
engine.AddParam("miller", new int[] { 1, 2, 3, 4, 5 });
engine.AddParam("smith", new int[] { 1, 2, 3, 4, 5 });
engine.AddRequire((int baker) => baker != 5);
engine.AddRequire((int cooper) => cooper != 1);
engine.AddRequire((int fletcher) => fletcher != 1 && fletcher != 5);
engine.AddRequire((int miller, int cooper) => miller > cooper);
engine.AddRequire((int smith, int fletcher) =>
smith != fletcher + 1
&& smith != fletcher - 1);
engine.AddRequire((int fletcher, int cooper) => fletcher != cooper + 1
&& fletcher != cooper - 1);
engine.AddRequire((int baker, int cooper, int fletcher, int miller, int smith) =>
baker != cooper && baker != fletcher && baker != miller
&& baker != smith && cooper != fletcher && cooper != miller
&& cooper != smith && fletcher != miller && fletcher != smith && miller != smith);
engine.EachResult(
result =>
Console.WriteLine("baker: {0}, cooper: {1}, fletcher: {2}, miller: {3}, smith: {4}",
result["baker"],
result["cooper"],
result["fletcher"],
result["miller"],
result["smith"])
);
}
// 八皇后問題的解法
public static void Test3()
{
var engine = new NonDeterministicEngine();
engine.AddParam("a", new int[] { 1, 2, 3, 4, 5, 6, 7, 8 });
engine.AddParam("b", new int[] { 1, 2, 3, 4, 5, 6, 7, 8 });
engine.AddParam("c", new int[] { 1, 2, 3, 4, 5, 6, 7, 8 });
engine.AddParam("d", new int[] { 1, 2, 3, 4, 5, 6, 7, 8 });
engine.AddParam("e", new int[] { 1, 2, 3, 4, 5, 6, 7, 8 });
engine.AddParam("f", new int[] { 1, 2, 3, 4, 5, 6, 7, 8 });
engine.AddParam("g", new int[] { 1, 2, 3, 4, 5, 6, 7, 8 });
engine.AddParam("h", new int[] { 1, 2, 3, 4, 5, 6, 7, 8 });
engine.AddRequire((int a, int b, int c, int d, int e, int f, int g, int h) =>
a != b && a != c && a != d
&& a != e && a != f && a != g && a != h
&& b != c && b != d && b != e && b != f && b != g && b != h
&& c != d && c != e && c != f && c != g && c != h
&& d != e && d != f && d != g && d != h
&& e != f && e != g && e != h
&& f != g && f != h
&& g != h
&& NotInTheSameDiagonalLine(new int[] { a, b, c, d, e, f, g, h }));
engine.EachResult(
result =>
Console.WriteLine("(1,{0}), (2,{1}), (3,{2}), (4,{3}), (5,{4}), (6,{5}), (7,{6}), (8,{7})",
result["a"],
result["b"],
result["c"],
result["d"],
result["e"],
result["f"],
result["g"],
result["h"])
);
}
static bool NotInTheSameDiagonalLine(int[] cols)
{
for (int i = 0; i < cols.Length - 1; i++)
{
for (int j = i + 1; j < cols.Length; j++)
{
if (j - i == Math.Abs(cols[j] - cols[i]))
return false;
}
}
return true;
}
public static void Benchmarking(Action f, string messageFormat)
{
DateTime time1 = DateTime.Now;
f();
DateTime time2 = DateTime.Now;
Console.WriteLine(messageFormat, (time2 - time1).TotalMilliseconds);
}
}
}
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Collections;
namespace NonDeterministicEngineCS
{
public class Param
{
public string Name
{
get;
set;
}
public IEnumerator Values
{
get;
set;
}
}
}
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace NonDeterministicEngineCS
{
public abstract class Condition
{
public IList<string> ParamNames
{
get;
protected set;
}
public abstract bool Call(params object[] args);
public Condition(Delegate predicate)
{
ParamNames = predicate.Method.GetParameters().Select(p => p.Name).ToArray();
}
}
public class Condition<T> : Condition
{
public Condition(Func<T, bool> predicate)
: base(predicate)
{
m_func = predicate;
}
Func<T, bool> m_func;
public override bool Call(params object[] args)
{
return m_func((T)args[0]);
}
}
public class Condition<T1, T2> : Condition
{
public Condition(Func<T1, T2, bool> predicate)
: base(predicate)
{
m_func = predicate;
}
Func<T1, T2, bool> m_func;
public override bool Call(params object[] args)
{
return m_func((T1)args[0], (T2)args[1]);
}
}
public class Condition<T1, T2, T3> : Condition
{
public Condition(Func<T1, T2, T3, bool> predicate)
: base(predicate)
{
m_func = predicate;
}
Func<T1, T2, T3, bool> m_func;
public override bool Call(params object[] args)
{
return m_func((T1)args[0], (T2)args[1], (T3)args[2]);
}
}
public class Condition<T1, T2, T3, T4> : Condition
{
public Condition(Func<T1, T2, T3, T4, bool> predicate)
: base(predicate)
{
m_func = predicate;
}
Func<T1, T2, T3, T4, bool> m_func;
public override bool Call(params object[] args)
{
return m_func((T1)args[0], (T2)args[1], (T3)args[2], (T4) args[3]);
}
}
public class Condition<T1, T2, T3, T4, T5> : Condition
{
public Condition(Func<T1, T2, T3, T4, T5, bool> predicate)
: base(predicate)
{
m_func = predicate;
}
Func<T1, T2, T3, T4, T5, bool> m_func;
public override bool Call(params object[] args)
{
return m_func((T1)args[0], (T2)args[1], (T3)args[2], (T4)args[3], (T5)args[4]);
}
}
public class Condition<T1, T2, T3, T4, T5, T6> : Condition
{
public Condition(Func<T1, T2, T3, T4, T5, T6, bool> predicate)
: base(predicate)
{
m_func = predicate;
}
Func<T1, T2, T3, T4, T5, T6, bool> m_func;
public override bool Call(params object[] args)
{
return m_func((T1)args[0], (T2)args[1], (T3)args[2], (T4)args[3], (T5)args[4], (T6)args[5]);
}
}
public class Condition<T1, T2, T3, T4, T5, T6, T7> : Condition
{
public Condition(Func<T1, T2, T3, T4, T5, T6, T7, bool> predicate)
: base(predicate)
{
m_func = predicate;
}
Func<T1, T2, T3, T4, T5, T6, T7, bool> m_func;
public override bool Call(params object[] args)
{
return m_func((T1)args[0], (T2)args[1], (T3)args[2], (T4)args[3], (T5)args[4], (T6)args[5], (T7)args[6]);
}
}
public class Condition<T1, T2, T3, T4, T5, T6, T7, T8> : Condition
{
public Condition(Func<T1, T2, T3, T4, T5, T6, T7, T8, bool> predicate)
: base(predicate)
{
m_func = predicate;
}
Func<T1, T2, T3, T4, T5, T6, T7, T8, bool> m_func;
public override bool Call(params object[] args)
{
return m_func((T1)args[0], (T2)args[1], (T3)args[2], (T4)args[3], (T5)args[4], (T6)args[5], (T7)args[6], (T8)args[7]);
}
}
}
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Collections;
using System.Threading.Tasks;
using System.Linq.Expressions;
namespace NonDeterministicEngineCS
{
public class NonDeterministicEngine
{
private List<Param> m_paramDict = new List<Param>();
private List<Condition> m_predicateDict = new List<Condition>();
public void AddParam(string name, IEnumerable values)
{
m_paramDict.Add(new Param { Name = name, Values = values.GetEnumerator() });
}
#region Add Require
public void AddRequire<T>(Func<T, bool> predicate)
{
m_predicateDict.Add(new Condition<T>(predicate));
}
public void AddRequire<T1, T2>(Func<T1, T2, bool> predicate)
{
m_predicateDict.Add(new Condition<T1, T2>(predicate));
}
public void AddRequire<T1, T2, T3>(Func<T1, T2, T3, bool> predicate)
{
m_predicateDict.Add(new Condition<T1, T2, T3>(predicate));
}
public void AddRequire<T1, T2, T3, T4>(Func<T1, T2, T3, T4, bool> predicate)
{
m_predicateDict.Add(new Condition<T1, T2, T3, T4>(predicate));
}
public void AddRequire<T1, T2, T3, T4, T5>(Func<T1, T2, T3, T4, T5, bool> predicate)
{
m_predicateDict.Add(new Condition<T1, T2, T3, T4, T5>(predicate));
}
public void AddRequire<T1, T2, T3, T4, T5, T6>(Func<T1, T2, T3, T4, T5, T6, bool> predicate)
{
m_predicateDict.Add(new Condition<T1, T2, T3, T4, T5, T6>(predicate));
}
public void AddRequire<T1, T2, T3, T4, T5, T6, T7>(Func<T1, T2, T3, T4, T5, T6, T7, bool> predicate)
{
m_predicateDict.Add(new Condition<T1, T2, T3, T4, T5, T6, T7>(predicate));
}
public void AddRequire<T1, T2, T3, T4, T5, T6, T7, T8>(Func<T1, T2, T3, T4, T5, T6, T7, T8, bool> predicate)
{
m_predicateDict.Add(new Condition<T1, T2, T3, T4, T5, T6, T7, T8>(predicate));
}
#endregion
public IEnumerable<Dictionary<string, object>> GetResults()
{
var em = new CombinationEnumerable(this);
foreach (var item in em)
{
if (Satisfy(item))
yield return item;
}
}
public void EachResult(Action<Dictionary<string, object>> action)
{
var em = new CombinationEnumerable(this);
Parallel.ForEach(
em,
result =>
{
if (Satisfy(result))
{
action(result);
}
}
);
}
bool Satisfy(Dictionary<string, object> result)
{
foreach (Condition item in m_predicateDict)
{
var args = item.ParamNames.Select(
name => result[name]
).ToArray();
if (item.Call(args))
continue;
return false;
}
return true;
}
private class CombinationEnumerable : IEnumerable<Dictionary<string, object>>
{
NonDeterministicEngine m_engine;
public CombinationEnumerable(NonDeterministicEngine engine)
{
m_engine = engine;
}
public IEnumerator<Dictionary<string, object>> GetEnumerator()
{
return new CombinationEnumerator(m_engine);
}
IEnumerator IEnumerable.GetEnumerator()
{
return new CombinationEnumerator(m_engine);
}
}
/// <summary>
/// 組合多個 iterator 為一個複合的 iterator.
/// MoveNext 實現為：移動到下一個所有變數值可能的組合。
/// </summary>
private class CombinationEnumerator : IEnumerator<Dictionary<string, object>>
{
private bool m_firstTime = true;
private NonDeterministicEngine m_target;
public CombinationEnumerator(NonDeterministicEngine engine)
{
m_target = engine;
}
public void Dispose()
{
}
public Dictionary<string, object> GetCurrent()
{
if (IterationOver)
return null;
return m_target.m_paramDict.ToDictionary
(param => param.Name, param => param.Values.Current);
}
public bool MoveNext()
{
if (IterationOver)
return false;
if (m_firstTime)
{
// 首次執行時，需要將所有變數的 enumerator 都前進到起始位置
foreach (Param item in m_target.m_paramDict)
{
item.Values.MoveNext();
}
m_firstTime = false;
return true;
}
// 首先嚐試最後一個變數的 iterator，看能否 MoveNext() （是否還有沒有嘗試過的值）。
int iterIndex = m_target.m_paramDict.Count - 1;
bool canMoveNext = m_target.m_paramDict[iterIndex].Values.MoveNext();
if (canMoveNext)
return true;
// 否則依次回溯到前一個變數，看該變數的 iterator 能否 MoveNext()
while (!canMoveNext)
{
iterIndex--;
// 表明已嘗試了所有變數的所有可能值，退無可退，則終止列舉過程。
if (iterIndex == -1)
{
IterationOver = true;
return false;
}
canMoveNext = m_target.m_paramDict[iterIndex].Values.MoveNext();
// 如果往前退到某個可以前進的位置
if (canMoveNext)
{
// 則需要將這個位置之後的所有其他變數的 iterator 復位，並前進到第一種可能性。
for (int i = iterIndex + 1; i < m_target.m_paramDict.Count; i++)
{
var iter = m_target.m_paramDict[i].Values;
iter.Reset();
iter.MoveNext();
}
return true;
}
}
return false;
}
public void Reset()
{
IterationOver = false;
m_firstTime = true;
foreach (var param in m_target.m_paramDict)
{
param.Values.Reset();
}
}
public Dictionary<string, object> Current
{
get
{
return GetCurrent();
}
}
/// <summary>
/// 標記列舉是否已經結束
/// </summary>
public bool IterationOver
{
get;
set;
}
object IEnumerator.Current
{
get
{
return GetCurrent();
}
}
}
}
}