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  1. #include <iostream>
  2. using namespace std;
  3. const int mod = 1000000007;
  4. int a[10000];
  5. int solve(int n){
  6. 	int *A = a + n;
  7. 	A[0] = 1; A[-1] = 0;
  8. 	int k = 0, e = 1;
  9. 	for (int i = 0; i <= n; ++i){
  10. 		int Am = 0; 
  11. 		A[k + e] = 0; 
  12. 		e = -e;
  13. 		for (int j = 0; j <= i; ++j){
  14. 			Am += A[k]; 
  15. 			if (Am >= mod) Am -= mod;
  16. 			A[k] = Am; 
  17. 			k += e;
  18. 		}
  19. 	}
  20. 	return n % 2 ? A[n / 2] : A[-n / 2];
  21. }
  22.  
  23. int main()
  24. {
  25. 	int n; 
  26. 	cin >> n;
  27. 	cout << solve(n) << endl;
  28. 	return 0;
  29. }
  30.  
Success #stdin #stdout 0s 3380KB
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https://ideone.com/No9H0A
language:
C++ (gcc 8.3)
created:
10 years ago
visibility:
public

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