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  1. #include <bits/stdc++.h>
  2. #include <ext/pb_ds/assoc_container.hpp>
  3. #include <ext/pb_ds/tree_policy.hpp>
  4.  
  5. using namespace std;
  6. using namespace __gnu_pbds;
  7.  
  8. #define fi first
  9. #define se second
  10. #define mp make_pair
  11. #define pb push_back
  12. #define fbo find_by_order
  13. #define ook order_of_key
  14.  
  15. typedef long long ll;
  16. typedef pair<int,int> ii;
  17. typedef vector<int> vi;
  18. typedef long double ld; 
  19. typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> pbds;
  20. typedef set<int>::iterator sit;
  21. typedef map<int,int>::iterator mit;
  22. typedef vector<int>::iterator vit;
  23.  
  24. const int N = 100001;
  25. int a[N+1];
  26. const int MOD = 1e9 + 7;
  27. ll dp[N+1];
  28.  
  29. int main()
  30. {
  31. 	ios_base::sync_with_stdio(0); cin.tie(0);
  32. 	int n; cin >> n;
  33. 	for(int i = 0; i < n; i++)
  34. 	{
  35. 		cin >> a[i];
  36. 	}
  37. 	dp[0] = 2;
  38. 	for(int i = 1; i < n; i++)
  39. 	{
  40. 		dp[i] = dp[i-1];
  41. 		if(a[i-1]<=a[i])
  42. 		{
  43. 			dp[i]+=dp[i-1];
  44. 		}
  45. 		else
  46. 		{
  47. 			if(i>=2) dp[i] += dp[i-2];
  48. 			else dp[i]++;
  49. 		}
  50. 		dp[i]%=MOD;
  51. 	}
  52. 	cout<<dp[n-1]<<'\n';
  53. }
  54.  
Runtime error #stdin #stdout 1.35s 4636KB
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https://ideone.com/TnWjwP
language:
C++14 (gcc 8.3)
created:
7 years ago
visibility:
public

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