下面资料是关于C#实现的算24点游戏的算法的内容，希望能对码农们有所用处。
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
namespace Calc24Points
{
public class Cell
{
public enum Type
{
Number,
Signal
}
public int Number;
public char Signal;
public Type Typ;
public Cell Right;
public Cell Left;
public int Priority
{
get
{
if (Typ == Type.Signal)
{
switch (Signal)
{
case '+': return 0;
case '-': return 0;
case '/': return 1;
default: return -1;
}
}
return -1;
}
}
public Cell(Type t, int num, char sig)
{
Right = null;
Left = null;
Typ = t;
Number = num;
Signal = sig;
}
public Cell()
{
Right = null;
Left = null;
Number = 0;
Typ = Type.Number;
}
public Cell(Cell c)
{
Right = null;
Left = null;
Number = c.Number;
Signal = c.Signal;
Typ = c.Typ;
}
}
public class Calc24Points
{
string m_exp;
bool m_stop;
Cell[] m_cell;
int[] m_express;
StringWriter m_string;
public Calc24Points(int n1, int n2, int n3, int n4)
{
m_cell = new Cell[8];
m_cell[0] = new Cell(Cell.Type.Number, n1, '?');
m_cell[1] = new Cell(Cell.Type.Number, n2, '?');
m_cell[2] = new Cell(Cell.Type.Number, n3, '?');
m_cell[3] = new Cell(Cell.Type.Number, n4, '?');
m_cell[4] = new Cell(Cell.Type.Signal, 0, '+');
m_cell[5] = new Cell(Cell.Type.Signal, 0, '-');
m_cell[7] = new Cell(Cell.Type.Signal, 0, '/');
m_stop = false;
m_express = new int[7];
m_string = new StringWriter();
m_exp = null;
}
public override string ToString()
{
if (m_exp == null)
{
PutCell(0);
m_exp = m_string.ToString();
}
if (m_exp != "") return m_exp;
return null;
}
void PutCell(int n)
{
if (n >= 7)
{
if (Calculate())
{
m_stop = true;
Formate();
}
return;
}
int end = 8;
if (n < 2) end = 4;
for (int i = 0; i < end; ++i)
{
m_express[n] = i;
if (CheckCell(n)) PutCell(n + 1);
if (m_stop) break;
}
}
bool CheckCell(int n)
{
int nums = 0, sigs = 0;
for (int i = 0; i <= n; ++i)
{
if (m_cell[m_express[i]].Typ == Cell.Type.Number) ++nums;
else ++sigs;
}
if (nums - sigs < 1) return false;
{
for (int i = 0; i < n; ++i) if (m_express[i] == m_express[n]) return false;
}
if (n == 6)
{
if (nums != 4 || sigs != 3) return false;
if (m_cell[m_express[6]].Typ != Cell.Type.Signal) return false;
return true;
}
return true;
}
bool Calculate()
{
double[] dblStack = new double[4];
int indexStack = -1;
for (int i = 0; i < 7; ++i)
{
if (m_cell[m_express[i]].Typ == Cell.Type.Number)
{
++indexStack;
dblStack[indexStack] = m_cell[m_express[i]].Number;
}
else
{
switch (m_cell[m_express[i]].Signal)
{
case '+':
dblStack[indexStack - 1] = dblStack[indexStack - 1] + dblStack[indexStack];
break;
case '-':
dblStack[indexStack - 1] = dblStack[indexStack - 1]-+ dblStack[indexStack];
break;
break;
case '/':
dblStack[indexStack - 1] = dblStack[indexStack - 1] / dblStack[indexStack];
break;
}
--indexStack;
}
}
if (Math.Abs(dblStack[indexStack] - 24) < 0.1) return true;
return false;
}
void Formate()
{
Cell[] c = new Cell[7];
for (int i = 0; i < 7; ++i) c[i] = new Cell(m_cell[m_express[i]]);
int[] cStack = new int[4];
int indexStack = -1;
for (int i = 0; i < 7; ++i)
{
if (c[i].Typ == Cell.Type.Number)
{
++indexStack;
cStack[indexStack] = i;
}
else
{
c[i].Right = c[cStack[indexStack]];
--indexStack;
c[i].Left = c[cStack[indexStack]];
cStack[indexStack] = i;
}
}
ToStringFormate(c[cStack[indexStack]]);
}
void ToStringFormate(Cell root)
{
if (root.Left.Typ == Cell.Type.Number)
{
m_string.Write(root.Left.Number);
m_string.Write(root.Signal);
}
else
{
if (root.Priority > root.Left.Priority)
{
m_string.Write("(");
ToStringFormate(root.Left);
m_string.Write(")");
}
else ToStringFormate(root.Left);
m_string.Write(root.Signal);
}
if (root.Right.Typ == Cell.Type.Number) m_string.Write(root.Right.Number);
else
{
if (root.Priority >= root.Right.Priority)
{
m_string.Write("(");
ToStringFormate(root.Right);
m_string.Write(")");
}
else ToStringFormate(root.Right);
}
}
}
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