1 #include <iostream> 2 #include <string> 3 #include <cstdlib> 4 #include <cmath> 5 using namespace std; 6 7 const double Threshold = 1E-6; 8 const int CardsNumber=4; 9 const int ResultValue = 24; 10 double numbers[CardsNumber]; 11 string result[CardsNumber]; 12 13 bool Points24(int n) 14 { 15 if (n == 1) 16 { 17 if (fabs(numbers[0] - ResultValue) < Threshold) 18 { 19 cout << result[0] << endl; 20 return true; 21 } 22 else 23 { 24 return false; 25 } 26 } 27 for (int i = 0; i < n; i++) 28 { 29 for (int j = i+1; j < n; j++) 30 { 31 double a, b; 32 string expa, expb; 33 a = numbers[i]; 34 b = numbers[j]; 35 numbers[j] = numbers[n - 1]; 36 37 expa = result[i]; 38 expb = result[j]; 39 result[j] = result[n - 1]; 40 41 numbers[i] = a + b; 42 result[i] = "(" + expa + "+" + expb + ")"; 43 if (Points24(n - 1)) 44 { 45 //cout << result[i]<<endl; 46 return true; 47 } 48 49 numbers[i] = a - b; 50 result[i] = "(" + expa + "-" + expb + ")"; 51 if (Points24(n - 1)) 52 { 53 return true; 54 } 55 56 numbers[i] = b - a; 57 result[i] = "(" + expb + "-" + expa + ")"; 58 if (Points24(n - 1)) 59 { 60 return true; 61 } 62 63 numbers[i] = a * b; 64 result[i] = "(" + expa + "*" + expb + ")"; 65 if (Points24(n - 1)) 66 { 67 return true; 68 } 69 70 if (b) 71 { 72 numbers[i] = a/b; 73 result[i] = "(" + expa + "/" + expb + ")"; 74 if (Points24(n - 1)) 75 { 76 return true; 77 } 78 } 79 if (a) 80 { 81 numbers[i] = b / a; 82 result[i] = "(" + expb + "/" + expa + ")"; 83 if (Points24(n - 1)) 84 { 85 return true; 86 } 87 } 88 numbers[i] = a; 89 numbers[j] = b; 90 result[i] = expa; 91 result[j] = expb; 92 } 93 } 94 return false; 95 96 97 } 98 int main() 99 { 100 int x; 101 for (int i = 0; i < CardsNumber; i++) 102 { 103 cout << "the NO." << i << " number is: "; 104 cin >> x; 105 numbers[i] = x; 106 char buffer[20]; 107 itoa(x,buffer,10); 108 result[i] = buffer; 109 } 110 if (Points24(CardsNumber)) 111 cout << "Success" << endl; 112 else cout << "Fail" << endl; 113 return 0; 114 }