fork download
copy 
  1. #include <bits/stdc++.h> 
  2.  
  3. using namespace std;  
  4.  
  5. typedef long long ll;  
  6. typedef pair<int, int> ii;  
  7.  
  8. const int INF = 1e9;  
  9. const ll LINF = 1e18;  
  10. const int N = 1e5 + 5; 
  11.  
  12. int n, L, R; 
  13. int a[N]; 
  14. ll pref[N]; 
  15.  
  16. struct Fenwick {
  17. 	int n; 
  18. 	vector<int> ft;  
  19.  
  20. 	Fenwick(int n) : n(n) {
  21. 		ft.resize(n, 0); 
  22. 	}
  23.  
  24. 	void update(int pos, int val) {
  25. 		for (; pos >= 0; pos = (pos & (pos + 1)) - 1) {
  26. 			ft[pos] += val; 
  27. 		}
  28. 	}
  29.  
  30. 	int get(int pos) {
  31. 		int ans = 0;  
  32. 		for (; pos < n; pos = pos | (pos + 1)) {
  33. 			ans += ft[pos];
  34. 		}
  35. 		return ans; 
  36. 	}
  37. }; 
  38.  
  39. ll countSum(ll X) {
  40. 	//     sum[i + 1..j] <= X
  41. 	// <=> pref[j] - pref[i] <= X 
  42. 	// <=> pref[i] >= pref[j] - X 
  43.  
  44. 	vector<ll> vals;  
  45. 	for (int i = 0; i <= n; i++) {
  46. 		vals.push_back(pref[i]); 
  47. 	}
  48. 	sort(vals.begin(), vals.end());  
  49. 	vals.resize(unique(vals.begin(), vals.end()) - vals.begin());  
  50.  
  51. 	Fenwick fenw(vals.size()); 
  52. 	ll ans = 0; 
  53. 	for (int j = 0; j <= n; j++) {
  54. 		// Giá trị nén của pref[i] nhỏ nhất >= pref[j] - X
  55. 		int u = lower_bound(vals.begin(), vals.end(), pref[j] - X) - vals.begin();
  56. 		ans += fenw.get(u);  
  57.  
  58. 		// Giá trị nén của pref[j]
  59. 		int v = lower_bound(vals.begin(), vals.end(), pref[j]) - vals.begin(); 
  60. 		fenw.update(v, 1); 
  61. 	}
  62.  
  63. 	return ans; 
  64. }
  65.  
  66. int main() {
  67. 	ios::sync_with_stdio(false); 
  68. 	cin.tie(nullptr);  	
  69. 	cin >> n >> L >> R;  
  70. 	for (int i = 1; i <= n; i++) cin >> a[i], pref[i] = pref[i - 1] + a[i]; 
  71.  
  72. 	ll ans = countSum(R) - countSum(L - 1);
  73.  
  74. 	cout << ans << '\n'; 
  75. }
  76.  
Success #stdin #stdout 0s 5320KB
comments (?)
stdin
copy 
4 2 4
1 2 3 4
stdout
copy 
4
https://ideone.com/C3SWtm
language:
C++14 (gcc 8.3)
created:
36 days 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!