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  1.  
  2. #include <iostream>
  3. #include <iomanip>
  4. #include <cstdlib>
  5. #include <ctime>
  6. #include <cmath>
  7. #include<fstream>
  8. #include<iomanip>
  9. using namespace std;
  10.  
  11.  
  12. // simulation de v.a.r. uniforme sur ]0,1[ :
  13. inline double unif_rand() {
  14.     return (rand() + 0.5)/(RAND_MAX + 1.0);
  15. }
  16.  
  17. class Alea {
  18.  public:
  19.     virtual double rand() const = 0;
  20. };
  21.  
  22. class AleaDiscret : public Alea {
  23.  public:
  24.     virtual double loi(int n) const = 0;
  25.     virtual double rand() const;
  26. };
  27.  
  28. double AleaDiscret::rand() const {
  29.     double y = unif_rand();
  30.     int x = 0;
  31.     double Fx = loi(0);
  32.     while ( y > Fx ) {
  33.         Fx += loi(++x);
  34.     }
  35.     return double(x);
  36. }
  37.  
  38. class Poisson : public AleaDiscret {
  39.     double lambda;
  40.  
  41.     double e_lbda;
  42.  public :
  43.     Poisson(double l = 1.0) : lambda(l) , e_lbda(exp(-l)) {}
  44.     virtual double loi(int n) const {
  45.         return e_lbda*pow(lambda,n)/tgamma(n+1);
  46.     }
  47.  
  48.   // plus rapide que AleaDiscret::rand()
  49.     virtual double rand() const;
  50. };
  51.  
  52. double Poisson::rand() const {
  53.     double x = 1;
  54.     int n = -1;
  55.     do {
  56.         x *= unif_rand();
  57.         ++n;
  58.     } while ( x > e_lbda );
  59.     return double(n);
  60. }
  61.  
  62. double moy(const Alea & a) {
  63.     const int N = 1000;
  64.     double s = 0.0;
  65.     for (int n = 0 ; n < N ; ++n)
  66.         s += a.rand();
  67.     return s/N;
  68. }
  69.  
  70. int main(){
  71.     double total=0;
  72.     double duration[100]; //這個100的數值可修改
  73.     int tmp=0, num;
  74.     Poisson poi(12);  //這個12的數值可修改
  75.     srand(int(time(0)));
  76.     do{
  77.         duration[tmp]=poi.rand();
  78.         total+=duration[tmp];
  79.         tmp++;
  80.     }while(total<=50); //這個50的數值可修改
  81.  
  82.  
  83.     for(int i=1; i<tmp; i++){
  84.         duration[i]+=duration[i-1];
  85.     }
  86.     cout<<tmp<<endl;
  87.     for(int i=0; i<tmp; i++){
  88.         cout<<duration[i]<<endl;
  89.     }
  90.     return 0;
  91. }
  92.  
Success #stdin #stdout 0.01s 2724KB
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https://ideone.com/XkMQH
language:
C++ (gcc 8.3)
created:
13 years ago
visibility:
public

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