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  1. #include<iostream>
  2. #include<algorithm>
  3. #include<cstdio>
  4. #include<cstring>
  5. #include<climits>
  6.  
  7. #define lli long long int
  8. #define mod 1000000007
  9.  
  10. using namespace std;
  11.  
  12. int n, k, d;
  13. lli dp[107][2];
  14.  
  15. lli recur(lli num, bool activated)
  16. {
  17. 	if(dp[num][activated]!=-1)
  18. 		return dp[num][activated];
  19.  
  20. 	if(num==0)
  21. 		{
  22. 			if(!activated)
  23. 				return 0;
  24. 			else
  25. 				return 1;
  26. 		}
  27.  
  28. 	lli ans=0, i;
  29.  
  30. 	for(i=1; i<=k; i++)
  31. 		if(num-i>=0)
  32. 			{
  33. 				if(i>=d)
  34. 					ans=(ans+recur(num-i, 1))%mod;
  35. 				else
  36. 					ans=(ans+recur(num-i, activated))%mod;
  37. 			}
  38. 		else
  39. 			break;
  40.  
  41. 	return dp[num][activated]=ans;
  42. }
  43.  
  44. int main()
  45. {
  46. 	lli ans, i;
  47.  
  48. 	for(i=0; i<107; i++)
  49. 		{
  50. 			dp[i][0]=-1;
  51. 			dp[i][1]=-1;
  52. 		}
  53.  
  54. 	cin >> n >> k >> d;		
  55.  
  56. 	ans=recur(n, 0);
  57.  
  58. 	cout << ans << endl;
  59.  
  60. 	return 0;
  61. }
Success #stdin #stdout 0s 3472KB
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https://ideone.com/bNdjSc
language:
C++14 (gcc 8.3)
created:
7 years ago
visibility:
secret

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