24点递归算法

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  1 #include <iostream>
  2 #include <string>
  3 #include <math.h>
  4 using namespace std;
  5 const  double Threshold = 1e-6;
  6 const int CardsNumber = 4;
  7 const int ResultValue = 24;
  8 double number[CardsNumber];
  9 string result[CardsNumber];
 10 bool PointGame(int n)
 11 {
 12      if(n == 1)
 13      {
 14           if(fabs(number[0] - ResultValue) < Threshold)
 15           {
 16                     cout << result[0] << endl;
 17                     return true;
 18           }
 19           else
 20           {
 21                     return false;
 22           }
 23      }
 24      
 25      for(int i = 0; i < n; i++)
 26      {
 27              for(int j = i +1 ; j < n; j++)
 28              {
 29                      double a, b;
 30                      string expa, expb;
 31                      a = number[i];
 32                      b = number[j];
 33                      number[j] = number[n - 1];
 34                      
 35                      expa = result[i];
 36                      expb = result[j];
 37                      result[j] = result[n-1];
 38                      number[i] = a + b;
 39                      result[i] = '(' + expa + '+' + expb + ')';
 40                      if(PointGame(n-1))
 41                      {
 42                           return true;
 43                      }
 44                      number[i] = a - b;
 45                      result[i] = '(' + expa + '-' + expb + ')';
 46                      if(PointGame(n-1))
 47                      {
 48                           return true;
 49                      }
 50                      number[i] = b - a;
 51                      result[i] = '(' + expb + '-' + expa + ')';
 52                      if(PointGame(n-1))
 53                      {
 54                           return true;
 55                      }
 56                      number[i] = a * b;
 57                      result[i] = '(' + expa + '*' + expb + ')';
 58                      if(PointGame(n-1))
 59                      {
 60                           return true;
 61                      }
 62                      if(b != 0)
 63                      {
 64                          number[i] = a / b;
 65                          result[i] = '(' + expa + '/' + expb + ')';
 66                          if(PointGame(n-1))
 67                          {
 68                               return true;
 69                          }
 70                      }                     
 71 
 72                      if(a != 0)
 73                      {
 74                          number[i] = b / a;
 75                          result[i] = '(' + expb + '/' + expa + ')';
 76                          if(PointGame(n-1))
 77                          {
 78                               return true;
 79                          }
 80                      }
 81                      
 82                      number[i] = a;
 83                      number[j] = b;
 84                      result[i] = expa;
 85                      result[j] = expb;
 86                      
 87              }
 88      }
 89      return false;
 90      
 91 }
 92 
 93 void main()
 94 {
 95     int x;
 96     for(int i =0; i< CardsNumber; i++)
 97     {
 98             cout << "the " << i << "the number: ";
 99             cin >> x;
100             number[i] = x;
101             result[i] = (char)(x + '0');
102     }
103     
104     if(PointGame(CardsNumber))
105     {
106          cout << "Success" << endl;
107          
108     }
109     else
110     {
111         cout << "failure" << endl;
112     }
113    
114 
115 }
posted @ 2012-05-29 13:57  Epirus  阅读(545)  评论(0)    收藏  举报