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  1. #include <stdio.h>
  2. #include <math.h>
  3.  
  4. double f(double x)
  5. {
  6. 	return pow(x, 3.0);
  7. }
  8.  
  9. int main()
  10. {
  11. 	const double ANS = 1.0 / 4.0; 
  12. 	double a = 0.0;
  13. 	int N, i;
  14. 	double x, r1, r2, d;
  15.  
  16. 	for (N=1 ; fabs(a - ANS) >= 0.001; N++ ) {
  17. 		d = 1.0 / (double)N;
  18. 		r1 = f(0.0);
  19. 		a = 0.0;
  20. 		for (i=1, x=d; i<=N; i++, x+=d) {
  21. 			r2 = f(x);
  22. 			a += ((r1 + r2) * d) / 2.0;
  23. 			r1 = r2;
  24. 		}
  25. 	}
  26. 	printf("%f\n", a);
  27. 	return 0;
  28. }
  29.  
Success #stdin #stdout 0.01s 2724KB
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https://ideone.com/WqmYZ
language:
C++ (gcc 8.3)
created:
12 years ago
visibility:
secret

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