C#实现的24点游戏实例详解

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 /// 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 /// 
 /// 数字a /// 数字b /// 数字c /// 数字d ///  ///  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; } /// 
 /// 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 /// 
 /// 数字1 /// 数字2 /// 数字3 /// 数字4 ///  ///  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++) {> /// 求两数进行某一四则运算后的结果 ///  /// 数字1 /// 数字2 /// （0-5分别代表：加、减、被减、乘以、除以、除） /// 返回的表达式 /// 数字1表达式 /// 数字2表达式 ///  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(); }