C#实现的24点游戏实例详解

/// <summary>/// 判断abcd四个数进行任意四则运算后能不能得出24，每个数字只能用一次/// </summary>/// <param name="a">数字a</param>/// <param name="b">数字b</param>/// <param name="c">数字c</param>/// <param name="d">数字d</param>/// <param name="expression"></param>/// <returns></returns>private static bool Try24(int a, int b, int c, int d, ref string expression){ //a字头 if (TryEach(a, b, c, d, ref expression)) return true; if (TryEach(a, b, d, c, ref expression)) return true; if (TryEach(a, c, b, d, ref expression)) return true; if (TryEach(a, c, d, b, ref expression)) return true; if (TryEach(a, d, b, c, ref expression)) return true; if (TryEach(a, d, c, b, ref expression)) return true; //b字头 if (TryEach(b, a, c, d, ref expression)) return true; if (TryEach(b, a, d, c, ref expression)) return true; if (TryEach(b, c, a, d, ref expression)) return true; if (TryEach(b, c, d, a, ref expression)) return true; if (TryEach(b, d, a, c, ref expression)) return true; if (TryEach(b, d, c, a, ref expression)) return true; //c字头 if (TryEach(c, a, b, d, ref expression)) return true; if (TryEach(c, a, d, b, ref expression)) return true; if (TryEach(c, b, a, c, ref expression)) return true; if (TryEach(c, b, c, a, ref expression)) return true; if (TryEach(c, d, a, b, ref expression)) return true; if (TryEach(c, d, b, a, ref expression)) return true; //d字头 if (TryEach(d, a, b, c, ref expression)) return true; if (TryEach(d, a, c, b, ref expression)) return true; if (TryEach(d, b, a, c, ref expression)) return true; if (TryEach(d, b, c, a, ref expression)) return true; if (TryEach(d, c, a, b, ref expression)) return true; if (TryEach(d, c, b, a, ref expression)) return true; return false;}/// <summary>/// 判断指定顺序的四个数abcd进行任意四则运算后能不能得出24，每个数字只能用一次/// </summary>/// <param name="a">数字1</param>/// <param name="b">数字2</param>/// <param name="c">数字3</param>/// <param name="d">数字4</param>/// <param name="expression"></param>/// <returns></returns>private static bool TryEach(int a, int b, int c, int d, ref string expression){ expression = ""; //两个数可以做6种运算：加、减、被减、乘以、除以、除 //四个数共可以进行6*6*6=216种不同次序的四则运算 //初始化数组 for (int i = 0; i < 6 * 6 * 6; i++) {  //a与b间的运算符：i / 36  //b与c间的运算符：i % 36 / 6  //c与d间的运算符：i % 6  //1.运算顺序：a和b，再和c，再和d  {   string expression1 = "", expression2 = "";   int temp1 = ResultOf(a, b, i / 36, ref expression1);   int temp2 = ResultOf(temp1, c, i % 36 / 6, ref expression2, expression1);   int result = ResultOf(temp2, d, i % 6, ref expression, expression2);   if (result == 24) return true;  }  //2.运算顺序：a和b，c和d，前面部分和后面部分  {   string expression1 = "", expression2 = "";   int temp1 = ResultOf(a, b, i / 36, ref expression1);   int temp2 = ResultOf(c, d, i % 6, ref expression2);   int result = ResultOf(temp1, temp2, i % 36 / 6,    ref expression, expression1, expression2);   if (result == 24) return true;  }  //3.运算顺序：b和c运算，再与a运算，再与d运算  {   string expression1 = "", expression2 = "";   int temp1 = ResultOf(b, c, i % 36 / 6, ref expression1);   int temp2 = ResultOf(a, temp1, i / 36, ref expression2, "", expression1);   int result = ResultOf(temp2, d, i % 6, ref expression, expression2);   if (result == 24) return true;  }  //4.运算顺序：b和c运算，再与d运算，再与a运算  {   string expression1 = "", expression2 = "";   int temp1 = ResultOf(b, c, i % 36 / 6, ref expression1);   int temp2 = ResultOf(temp1, d, i % 6, ref expression2, expression1);   int result = ResultOf(a, temp2, i / 36, ref expression, "", expression2);   if (result == 24) return true;  }  //5.运算顺序：c和d运算，再和b运算，再和a运算  {   string expression1 = "", expression2 = "";   int temp1 = ResultOf(c, d, i % 6, ref expression1);   int temp2 = ResultOf(b, temp1, i % 36 / 6, ref expression2, "", expression1);   int result = ResultOf(a, temp2, i / 36, ref expression, "", expression2);   if (result == 24) return true;  } } expression = "Abandoned"; return false;}/// <summary>/// 求两数进行某一四则运算后的结果/// </summary>/// <param name="x">数字1</param>/// <param name="y">数字2</param>/// <param name="method">（0-5分别代表：加、减、被减、乘以、除以、除）</param>/// <param name="expression">返回的表达式</param>/// <param name="expressionLeft">数字1表达式</param>/// <param name="expressionRight">数字2表达式</param>/// <returns></returns>private static int ResultOf(int x, int y, int method, ref string expression, string expressionLeft = "", string expressionRight = ""){ //左右表达式之前被判定为无效则不计算，除数为0时不计算 if (expressionLeft == "Abandoned" || expressionRight == "Abandoned" ||  (x == 0 && method == 5) || (y == 0 && method == 4)) {  expression = "Abandoned";  return -1; } int result = 0; switch (method) {  case 0:   {    //加    result = x + y;    expression = string.Format("{0}+{1}",     expressionLeft == "" ? x.ToString() : expressionLeft,     expressionRight == "" ? y.ToString() : expressionRight);   }   break;  case 1:   {    //减    result = x - y;    expression = string.Format("{0}-{1}",     expressionLeft == "" ? x.ToString() : expressionLeft,     expressionRight == "" ? y.ToString() : expressionRight);   }   break;  case 2:   {    //被减    result = y - x;    expression = string.Format("{1}-{0}",     expressionLeft == "" ? x.ToString() : expressionLeft,     expressionRight == "" ? y.ToString() : expressionRight);   }   break;  case 3:   {    //乘以    result = x * y;    expression = string.Format("({0})*({1})",     expressionLeft == "" ? x.ToString() : expressionLeft,     expressionRight == "" ? y.ToString() : expressionRight);   }   break;  case 4:   {    //除以    if (x % y == 0)    {     result = x / y;     expression = string.Format("({0})/({1})",      expressionLeft == "" ? x.ToString() : expressionLeft,      expressionRight == "" ? y.ToString() : expressionRight);    }    else    {     expression = "Abandoned";    }   }   break;  case 5:   {    //除    if (y % x == 0)    {     result = y / x;     expression = string.Format("({1})/({0})",      expressionLeft == "" ? x.ToString() : expressionLeft,      expressionRight == "" ? y.ToString() : expressionRight);    }    else    {     expression = "Abandoned";    }   }   break; } //运算不合法，则返回-1，表达式为Abandoned， if (expression == "Abandoned") {  return -1; } return result;}

static void Main(string[] args){ string s = ""; bool try24; try24 = Try24(1, 2, 3, 4, ref s); Console.WriteLine("1,2,3,4: " + s); try24 = Try24(1, 3, 5, 7, ref s); Console.WriteLine("1,3,5,7: " + s); try24 = Try24(2, 3, 6, 4, ref s); Console.WriteLine("2,3,6,4: " + s); try24 = Try24(5, 7, 9, 4, ref s); Console.WriteLine("5,7,9,4: " + s); try24 = Try24(6, 3, 4, 5, ref s); Console.WriteLine("6,3,4,5: " + s); try24 = Try24(9, 5, 2, 7, ref s); Console.WriteLine("9,5,2,7: " + s); try24 = Try24(4, 9, 8, 3, ref s); Console.WriteLine("4,9,8,3: " + s); try24 = Try24(4, 9, 8, 2, ref s); Console.WriteLine("4,9,8,2: " + s); try24 = Try24(10, 10, 10, 10, ref s); Console.WriteLine("10,10,10,10: " + s); Console.ReadLine();}