10，由系统给出正确答案 算法思路：当你希望获取更多的解或者更快的得到答案的话，就可以使用这个功能。我采用穷举的方法，让计算机列出参与运算的数字和符号的各种排列方式，并按照基本运算原则进行计算，最后详细分析了出现括号的各种情况，并以规定的格式进行输出。 新建一个Unit文件“UnitAnswer”，打开UnitAnswer.h，加入如下代码： //--------------------------------------------------------------------------- #ifndef UnitAnswerH #define UnitAnswerH   #include <vcl.h>   //穷举法列出参与运算的数字的各种排列方式 void CunShuZi(int num[]);   //回溯法输出各个可能的正确答案 void CunFuHao(int xuhao);   //根据序号返回对应的运算符 char FuHao(int i);   //计算当前四则运算表达式，并返回计算结果 int JiSuan(void);   //记录正确答案到文本文件中 void Print(int n); //--------------------------------------------------------------------------- #endif        然后切换到UnitAnswer.cpp，实现上述自定义函数。 //--------------------------------------------------------------------------- #pragma hdrstop   #include "UnitAnswer.h" //---------------------------------------------------------------------------   #pragma package(smart_init)   const int MAX = 4; //参与运算的数字和符号的数量 int shuZi[MAX];    //存储参与运算的数字 char suanFu[MAX];  //存储可能的运算符，共4个：+,-,*,/ int iFile;           //文件句柄 String str("");    //用来存储各个正确答案   //--------------------------------------------------------------------------- //穷举法列出参与运算的数字的各种排列方式 void CunShuZi(int num[]) {     DeleteFile("answer.txt");  //销毁原来的文本文件，以便记录本题的正确答案     iFile = FileOpen("answer.txt", fmOpenReadWrite);     if (iFile == -1)        //新建文件            iFile = FileCreate("answer.txt", fmOpenReadWrite);       int i, j, k;      for (i=0; i<MAX; i++)//穷举法列出参与运算数字的各种排列方式      {            shuZi[0] = num[i];           for (j=0; j<MAX; j++)         {                  if (i != j)               {                     shuZi[1] = num[j];                      for (k=0; k<MAX; k++)                      {                        if (i != k && j != k)                           {                               shuZi[2] = num[k];                                 shuZi[3] = num[6-i-j-k];                              CunFuHao(0);//存储运算符                     }                 }             }         }        }     //输出最后一个答案到对话框，若无解则对话框的内容为空白     MessageBox(NULL, str.c_str(), "答案", MB_OK);     //MessageBox(NULL, "无解", "答案", MB_OK);     FileClose(iFile); } //--------------------------------------------------------------------------- //回溯法输出各个可能的正确答案 void CunFuHao(int xuhao) {        int i;         for (i=0; i<=3; i++)      {           suanFu[xuhao] = FuHao(i);           if (xuhao < 2)           {                CunFuHao(xuhao+1);         }           else           {                  Print(JiSuan()); //记录当前正确答案         }      } } //--------------------------------------------------------------------------- //根据序号返回对应的运算符 char FuHao(int i) {      switch(i)      {           case 0: return '+';           case 1: return '-';           case 2: return '*';           case 3: return '/';      } } //--------------------------------------------------------------------------- //计算当前四则运算表达式，并返回计算结果 int JiSuan(void) {      int i;      int result, sum1, sum2;      int flag0, flag1, flag2;       //判断第一，二，三个运算符是否为乘除运算符      flag0 = (suanFu[0] == '*' || suanFu[0] == '/');      flag1 = (suanFu[1] == '*' || suanFu[1] == '/');      flag2 = (suanFu[2] == '*' || suanFu[2] == '/');        if (!flag0 && flag1 && !flag2)//型如(a+b)*(c+d)       {           if (suanFu[0] == '+')                     sum1 = shuZi[0] + shuZi[1];           else                  sum1 = shuZi[0] - shuZi[1];                      if (suanFu[2] == '+')                     sum2 = shuZi[2] + shuZi[3];           else                  sum2 = shuZi[2] - shuZi[3];                   if (suanFu[1] == '*')                     result = sum1 * sum2;           else if (sum2 != 0 && sum1%sum2 == 0 )                  result = sum1 / sum2; /*前后两个数必须能整除，且分母不为0*/             else                       /*否则返回值12345（表示无效）*/                    result = 12345;      }      if (result == 24) //得到型如(a+b)*(c+d)的答案         return 1;               if (suanFu[0] == '*' && suanFu[1] == '/' && !flag2)//型如a*b/(c+d)       {         result = shuZi[0] * shuZi[1];                   if (suanFu[2] == '+')                     sum1 = shuZi[2] + shuZi[3];           else                  sum1 = shuZi[2] - shuZi[3];                      if (sum1 != 0 && result%sum1 == 0 )                  result /= sum1; /*前后两个数必须能整除，且分母不为0*/         else                       /*否则返回值12345（表示无效）*/                    result = 12345;      }      if (result == 24)//得到型如a*b/(c+d)的答案         return 2;               if (suanFu[0] == '/' && !flag1 && !flag2)//型如a/(b+c)+d       {           if (suanFu[1] == '+')                     sum1 = shuZi[1] + shuZi[2];           else                  sum1 = shuZi[1] - shuZi[2];                      if (sum1 != 0 && shuZi[0]%sum1 == 0 )                  result = shuZi[0] / sum1; /*前后两个数必须能整除，且分母不为0*/         else                                       goto A;          if (suanFu[2] == '+')           result += shuZi[3];        else if (suanFu[2] == '-')           result -= shuZi[3];      } A:      if (result == 24) //得到型如a/(b+c)+d的答案         return 3;                 if (flag0 && !flag1 && flag2)//型如a*b+c*d       {         if (suanFu[0] == '*')                     sum1 = shuZi[0] * shuZi[1];           else if (shuZi[1] != 0 && shuZi[0]%shuZi[1] == 0 )                  sum1 = shuZi[0] / shuZi[1]; /*前后两个数必须能整除，且分母不为0*/             else                    goto B;              if (suanFu[2] == '*')                     sum2 = shuZi[2] * shuZi[3];           else if (shuZi[3] != 0 && shuZi[2]%shuZi[3] == 0 )                  sum2 = shuZi[2] / shuZi[3]; /*前后两个数必须能整除，且分母不为0*/             else                    goto B;                                 if (suanFu[1] == '+')               result = sum1 + sum2;          else              result = sum1 - sum2;      } B:        if (result == 24) //得到型如a*b+c*d的答案         return 4;          result = shuZi[0];      for (i=0; i<=2; i++)//其他形式      {          switch(suanFu[i])          {                    case '+':  result += shuZi[i+1]; break;                    case '-':  result -= shuZi[i+1]; break;                    case '*':  result *= shuZi[i+1]; break;                    case '/':  if (shuZi[i+1] != 0 && result%shuZi[i+1] == 0 )                                                   result /= shuZi[i+1]; /*前后两个数必须能整除，且分母不为0*/                                  else                       /*否则返回值12345（表示无效）*/                                               result = 12345;                            break;         }     }      if (result == 24) //得到其他形式的答案         return 5;       return 0;   //无解 } //--------------------------------------------------------------------------- //记录正确答案到文本文件中 void Print(int n) {     if (n == 0)  //无解则不记录，直接返回到CunFuHao函数        return;            str = "     ";      int flag0, flag1, flag2;       //判断第一，二，三个运算符是否为乘除运算符      flag0 = (suanFu[0] == '*' || suanFu[0] == '/');      flag1 = (suanFu[1] == '*' || suanFu[1] == '/');      flag2 = (suanFu[2] == '*' || suanFu[2] == '/');         if     (n == 1)     //型如(a+b)*(c+d)      {            str += "(";         str += shuZi[0];         str += suanFu[0];         str += shuZi[1];         str += ")";         str += suanFu[1];         str += "(";         str += shuZi[2];         str += suanFu[2];         str += shuZi[3];         str += ")";      }      else if      (n == 2)    //型如a*b/(c+d)      {         str += shuZi[0];         str += "*";         str += shuZi[1];         str += "/";         str += "(";         str += shuZi[2];         str += suanFu[2];         str += shuZi[3];         str += ")";      }      else if      (n == 3)      //型如a/(b+c)+d      {         str += shuZi[0];         str += "/";         str += "(";         str += shuZi[1];         str += suanFu[1];         str += shuZi[2];         str += ")";         str += suanFu[2];         str += shuZi[3];              }      else if (n==5 && !flag0 && flag1) //型如(a+b)*c+d      {           str += "(";         str += shuZi[0];         str += suanFu[0];         str += shuZi[1];         str += ")";         str += suanFu[1];         str += shuZi[2];         str += suanFu[2];         str += shuZi[3];      }      else if (n==5 && !flag1 && flag2)//型如(a+b+c)*d      {           str += "(";         str += shuZi[0];         str += suanFu[0];         str += shuZi[1];         str += suanFu[1];         str += shuZi[2];         str += ")";         str += suanFu[2];         str += shuZi[3];      }     else  //不带括号的情况      {            for (int i=0; i<=2; i++)           {                str += shuZi[i];                str += suanFu[i];           }         str += shuZi[3];      }     FileWrite(iFile, str.c_str(), str.Length());//记录正确答案     //MessageBox(NULL, str.c_str(), "答案", MB_OK); }   结语：        至此，实现了我想要的功能。        为了让您更好的参看这个程序，我给出UnitMain.h的内容。 //--------------------------------------------------------------------------- #ifndef UnitMainH #define UnitMainH //--------------------------------------------------------------------------- #include <Classes.hpp> #include <Controls.hpp> #include <StdCtrls.hpp> #include <Forms.hpp> #include <ExtCtrls.hpp> #include <jpeg.hpp> //--------------------------------------------------------------------------- class TForm1 : public TForm { __published:    // IDE-managed Components        TButton *Button1;        TButton *Button2;        TEdit *Edit1;        TImage *Image1;        TImage *Image2;        TImage *Image3;        TImage *Image4;        TLabel *Label5;        TTimer *Timer1;        void __fastcall Button1Click(TObject *Sender);        void __fastcall Button2Click(TObject *Sender);        void __fastcall FormCloseQuery(TObject *Sender, bool &CanClose);        void __fastcall Timer1Timer(TObject *Sender);        void __fastcall Edit1KeyPress(TObject *Sender, char &Key);        void __fastcall Edit1KeyDown(TObject *Sender, WORD &Key,           TShiftState Shift); private:    // User declarations        int ColorData[4];     int SpendTime;     bool IsInputValide();        bool RightBracket(const String & str); public:            // User declarations        __fastcall TForm1(TComponent* Owner); }; //--------------------------------------------------------------------------- extern PACKAGE TForm1 *Form1; //--------------------------------------------------------------------------- #endif                                                                                                                 goal00001111于2008-05-25 （全文完）

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