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  1. #include <bits/stdc++.h>
  2.  
  3. using namespace std;
  4.  
  5. class TestProctoring
  6. {
  7. public:
  8. 	double expectedTime (vector <int> p, vector <int> q)
  9. 	{
  10. 		int n = (int) (p.size ());
  11. 		int m = 1 << n;
  12. 		vector <double> w (n);
  13. 		for (int i = 0; i < n; i++)
  14. 		{
  15. 			w[i] = p[i];
  16. 			w[i] /= q[i];
  17. 		}
  18. 		double res = 0.0;
  19. 		for (int s = 1; s < m; s++)
  20. 		{
  21. 			double v = 0.0;
  22. 			double sign = -1.0;
  23. 			for (int i = 0; i < n; i++)
  24. 			{
  25. 				if (s & (1 << i))
  26. 				{
  27. 					v = v + w[i] - v * w[i];
  28. 					sign *= -1.0;
  29. 				}
  30. 			}
  31. 			res += sign * 1.0 / v;
  32. 		}
  33. 		return res;
  34. 	}
  35. };
  36.  
  37. int main ()
  38. {
  39. 	TestProctoring a;
  40. 	vector <int> t0 = { 2,  3,  5,  7, 11, 13, 17};
  41. 	vector <int> t1 = { 3,  5,  7, 11, 13, 17, 19};
  42. 	printf ("%.20f\n", a.expectedTime (t0, t1));
  43. 	return 0;
  44. }
  45.  
Success #stdin #stdout 0s 4456KB
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2.62994450659242495760
https://ideone.com/AYnDzW
language:
C++ (gcc 8.3)
created:
6 years ago
visibility:
secret

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