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  1. #include <iostream>
  2. #include <cmath>
  3. using namespace std;
  4. struct data {
  5. 	int sum, pref, suff, ans;
  6. };
  7. data combine (data l, data r) {
  8. 	data res;
  9. 	res.sum = l.sum + r.sum;
  10. 	res.pref = max (l.pref, l.sum + r.pref);
  11. 	res.suff = max (r.suff, r.sum + l.suff);
  12. 	res.ans = max (max (l.ans, r.ans), l.suff + r.pref);
  13. 	return res;
  14. }
  15. data make_data (int val) {
  16. 	data res;
  17. 	res.sum = val;
  18. 	res.pref = res.suff = res.ans = val;
  19. 	return res;
  20. }
  21. void build (int a[], int v, int tl, int tr, data t[]) {
  22. 	if (tl == tr)
  23. 		t[v] = make_data (a[tl]);
  24. 	else {
  25. 		int tm = (tl + tr) / 2;
  26. 		build (a, v*2, tl, tm, t);
  27. 		build (a, v*2+1, tm+1, tr, t);
  28. 		t[v] = combine (t[v*2], t[v*2+1]);
  29. 	}
  30. }
  31. void update (int v, int tl, int tr, int pos, int new_val, data t[]) {
  32. 	if (tl == tr)
  33. 		t[v] = make_data (new_val);
  34. 	else {
  35. 		int tm = (tl + tr) / 2;
  36. 		if (pos <= tm)
  37. 			update (v*2, tl, tm, pos, new_val, t);
  38. 		else
  39. 			update (v*2+1, tm+1, tr, pos, new_val, t);
  40. 		t[v] = combine (t[v*2], t[v*2+1]);
  41. 	}
  42. }
  43. data query (int v, int tl, int tr, int l, int r, data t[]) {
  44. 	if (l == tl && tr == r)
  45. 		return t[v];
  46. 	int tm = (tl + tr) / 2;
  47. 	if (r <= tm)
  48. 		return query (v*2, tl, tm, l, r, t);
  49. 	if (l > tm)
  50. 		return query (v*2+1, tm+1, tr, l, r, t);
  51. 	return combine (
  52. 		query (v*2, tl, tm, l, tm, t),
  53. 		query (v*2+1, tm+1, tr, tm+1, r, t)
  54. 	);
  55. }
  56.  
  57. int main() {
  58. 	int n, m, x, y;
  59. 	cin >> n;
  60. 	int* a = new int[n];
  61. 	for(int i = 0; i < n; i++) {
  62. 		cin >> a[i];
  63. 	}
  64. 	data* t = new data[4*n];
  65. 	build(a, 1, 0, n-1, t);
  66. 	cin >> m ;
  67. 	bool oper;
  68. 	for(int i = 0; i < m; i++) {
  69. 		cin >> oper >> x >> y;
  70. 		if(!oper) {
  71. 			update (1, 0, n-1, x-1, y, t);
  72. 		} else if(oper) {
  73. 			cout << query (1, 0, n-1, x-1, y-1, t).ans << endl;
  74.  
  75. 		}
  76. 	}
  77. 	return 0;
  78. }
Success #stdin #stdout 0s 3464KB
comments (?)
stdin
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4
1 2 3 4
4
1 1 3
0 3 -3
1 2 4
1 3 3
stdout
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6
4
-3
https://ideone.com/xejONQ
2907
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
secret

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