fork download 
  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. const int N = 2;
  5.  
  6. struct matrix
  7. {
  8. 	double x[N+1][N+1];
  9. 	matrix(){memset(x, 0, sizeof(x));}
  10. 	matrix(double init)
  11. 	{
  12. 		memset(x, 0, sizeof(x));
  13. 		for(int i = 1; i <= N; i++)
  14. 			x[i][i] = init;
  15. 	}
  16. 	matrix operator *(matrix that)
  17. 	{
  18. 		matrix ret;
  19. 		for(int i = 1; i <= N; i++)
  20. 			for(int j = 1; j <= N; j++)
  21. 				for(int k = 1; k <= N; k++)
  22. 					ret.x[i][j] = (ret.x[i][j] + x[i][k] * that.x[k][j]);
  23. 		return ret;
  24. 	}	
  25. }I(1);
  26.  
  27. matrix power(matrix b, long long e)
  28. {
  29. 	matrix ret = I;
  30. 	while(e)
  31. 	{
  32. 		if(e&1) ret = ret * b;
  33. 		b = b * b;
  34. 		e /= 2;
  35. 	}
  36. 	return ret;
  37. }
  38.  
  39. double p;
  40.  
  41. double prob(int n, int k)
  42. {
  43. 	if(k > n) return 1;
  44. 	if(k < 1) return 0;
  45. 	matrix trans, init;
  46. 	trans.x[1][1] = 1/p; trans.x[1][2] = (p-1)/p; trans.x[2][1] = 1;
  47. 	init.x[1][1] = 1; init.x[2][1] = 0;
  48. 	init.x[1][1] = 1 / (power(trans, n) * init).x[1][1];
  49. 	return (power(trans, k-1) * init).x[1][1];
  50. }
  51.  
  52. class CatsOnTheCircle
  53. {
  54. 	public: double getProb(int N, int K, int _p)
  55. 	{
  56. 		p = _p / 1000000000.0;
  57. 		if(p < 0.5)
  58. 		{
  59. 			p = 1 - p;
  60. 			K = N - K;
  61. 		}
  62. 		double probR = prob(N-3, N-K-1);
  63. 		double probL = 1 - probR;
  64. 		if(probR < 0 || probR > 1) // INF
  65. 			return 0;
  66. 		return probR * (1 - prob(N-2, N-2)) + probL * prob(N-2, 1);
  67. 	}
  68. };
Compilation error #stdin compilation error #stdout 0s 0KB
comments (?)
stdin 
Standard input is empty
compilation info 
/usr/lib/gcc/i586-linux-gnu/5/../../../i386-linux-gnu/crt1.o: In function `_start':
(.text+0x18): undefined reference to `main'
collect2: error: ld returned 1 exit status
stdout 
Standard output is empty
https://ideone.com/Eeropa
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
secret

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!