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  1. /*
  2. * @Author: hungeazy
  3. * @Date:   2025-11-21 13:58:46
  4. * @Last Modified by:   hungeazy
  5. * @Last Modified time: 2025-11-21 14:37:47
  6. */
  7. #include <bits/stdc++.h>
  8. #include <ext/pb_ds/assoc_container.hpp> 
  9. #include <ext/pb_ds/tree_policy.hpp> 
  10. // #pragma GCC optimize("O3")  
  11. // #pragma GCC optimize("unroll-loops")  
  12. // #pragma GCC target("avx2,bmi,bmi2,popcnt,lzcnt")  
  13. using namespace std;
  14. using namespace __gnu_pbds; 
  15. bool M1;
  16. #define fast ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
  17. #define int long long
  18. #define ll long long 
  19. #define ull unsigned long long
  20. #define sz(x) x.size()
  21. #define sqr(x) (1LL * (x) * (x))
  22. #define all(x) x.begin(), x.end()
  23. #define fill(f,x) memset(f,x,sizeof(f))
  24. #define FOR(i,l,r) for(int i=l;i<=r;i++)
  25. #define FOD(i,r,l) for(int i=r;i>=l;i--)
  26. #define debug(x) cout << #x << " = " << x << '\n'
  27. #define ii pair<int,int>
  28. #define iii pair<int,ii>
  29. #define di pair<ii,ii>
  30. #define vi vector<int>
  31. #define vii vector<ii>
  32. #define mii map<int,int>
  33. #define fi first
  34. #define se second
  35. #define pb push_back
  36. #define MOD 1000000007
  37. #define __lcm(a,b) (1ll * ((a) / __gcd((a), (b))) * (b))
  38. #define YES cout << "YES\n"
  39. #define NO cout << "NO\n"
  40. #define MASK(i) (1LL << (i))
  41. #define c_bit(i) __builtin_popcountll(i)
  42. #define BIT(x,i) ((x) & MASK(i))
  43. #define SET_ON(x,i) ((x) | MASK(i))
  44. #define SET_OFF(x,i) ((x) & ~MASK(i))
  45. #define oo 1e18
  46. #define name ""
  47. #define endl '\n'
  48. #define memory() cerr << abs(&M2-&M1)/1024.0/1024 << " MB" << endl
  49. #define time() cerr << endl << "-------------Time:" << 1000.0 * clock() / CLOCKS_PER_SEC << "ms." << endl
  50. template<typename T> bool maximize(T &res, const T &val) { if (res < val){ res = val; return true; }; return false; }
  51. template<typename T> bool minimize(T &res, const T &val) { if (res > val){ res = val; return true; }; return false; }
  52. template <class T> using ordered_set = tree <T, null_type, less_equal <T>, rb_tree_tag,tree_order_statistics_node_update>;
  53. const int N = (int)1e5+10;
  54. int n,a[N];
  55.  
  56. namespace sub1 {
  57.  
  58. 	int pre[N];
  59.  
  60. 	bool approved() {
  61. 		return n <= 5e3;
  62. 	}
  63.  
  64. 	void solve(void)
  65. 	{
  66. 		FOR(i,1,n) pre[i] = pre[i-1]+a[i];
  67. 		int ans = -oo;
  68. 		FOR(l,1,n)
  69. 		{
  70. 			int sum = 0;
  71. 			FOR(r,l,n)
  72. 			{
  73. 				sum += pre[r]-pre[l-1];
  74. 				maximize(ans,sum);
  75. 			}
  76. 		}
  77. 		cout << ans;
  78. 	}
  79.  
  80. }
  81.  
  82. namespace sub2 {
  83.  
  84. 	int pre[N],preMul[N];
  85. 	/*
  86. 		pre[i]+pre[i]+pre[i+1]+..+pre[i]+...+pre[j]
  87. 		-> (i+1)*pre[i]-preMul[i]
  88. 		a = pre[i]
  89. 		b = -preMul[i]
  90. 		Phương trình quy về ax+b, đưa lên Lichao Tree để xử lí, tìm x min
  91. 	*/
  92. 	struct Line {
  93. 		int a,b;
  94. 		Line() {a = 0; b = oo;}
  95. 		Line(int _a, int _b):
  96. 			a(_a), b(_b) {};
  97. 		int get(int x) {
  98. 			return a*x+b;
  99. 		}
  100. 	};
  101.  
  102. 	struct LichaoTree {
  103. 		vector<Line> st;
  104. 		int n;
  105.  
  106. 		LichaoTree() {};
  107. 		LichaoTree(int _n):
  108. 			n(_n), st((_n<<2)+1,Line()) {};
  109.  
  110. 		void update(int id, int l, int r, Line L)
  111. 		{
  112. 			if (l == r)
  113. 			{
  114. 				if (st[id].get(l) > L.get(l))
  115. 					swap(st[id],L);
  116. 				return;
  117. 			}
  118. 			int mid = (l+r)>>1;
  119. 			if (st[id].a > L.a) swap(st[id],L);
  120. 			if (st[id].get(mid) > L.get(mid))
  121. 			{
  122. 				swap(st[id],L);
  123. 				update(id<<1|1,mid+1,r,L);
  124. 			}
  125. 			else update(id<<1,l,mid,L);
  126. 		}
  127.  
  128. 		int get(int id, int l, int r, int x) 
  129. 		{
  130. 			if (l == r) return st[id].get(x);
  131. 			int mid = (l+r)>>1;
  132. 			if (x <= mid) return min(st[id].get(x),get(id<<1,l,mid,x));
  133. 			else return min(st[id].get(x),get(id<<1|1,mid+1,r,x));
  134. 		}
  135. 	} LCT;
  136.  
  137. 	void solve(void)
  138. 	{
  139. 		LCT = LichaoTree(n+1);
  140. 		FOR(i,1,n)
  141. 		{
  142. 			pre[i] = pre[i-1]+a[i];
  143. 			preMul[i] = preMul[i-1]+i*a[i];
  144. 		}
  145. 		int ans = 0, mn = oo;
  146. 		LCT.update(1,1,n+1,Line(0,0));
  147. 		FOR(i,1,n)
  148. 		{
  149. 			int cur = (i+1)*pre[i]-preMul[i];
  150. 			int val = LCT.get(1,1,n+1,i+1);
  151. 			maximize(ans,cur-val);
  152. 			LCT.update(1,1,n+1,Line(pre[i],-preMul[i]));
  153. 		}
  154. 		cout << ans;
  155. 	}
  156.  
  157. }
  158.  
  159. bool M2;
  160. signed main()
  161. {
  162.     fast;
  163.     if (fopen(name".inp","r"))
  164.     {
  165.     	freopen(name".inp","r",stdin);
  166.     	freopen(name".out","w",stdout);
  167.     }
  168.     cin >> n;
  169.     FOR(i,1,n) cin >> a[i];
  170.     if (sub1::approved()) return sub1::solve(), time(), memory(), 0;
  171.     sub2::solve();
  172.     time();
  173.     memory();
  174.     return 0;
  175. }
  176. // ██░ ██  █    ██  ███▄    █   ▄████
  177. //▓██░ ██▒ ██  ▓██▒ ██ ▀█   █  ██▒ ▀█▒
  178. //▒██▀▀██░▓██  ▒██░▓██  ▀█ ██▒▒██░▄▄▄░
  179. //░▓█ ░██ ▓▓█  ░██░▓██▒  ▐▌██▒░▓█  ██▓
  180. //░▓█▒░██▓▒▒█████▓ ▒██░   ▓██░░▒▓███▀▒
  181. // ▒ ░░▒░▒░▒▓▒ ▒ ▒ ░ ▒░   ▒ ▒  ░▒   ▒
  182. // ▒ ░▒░ ░░░▒░ ░ ░ ░ ░░   ░ ▒░  ░   ░
  183. // ░  ░░ ░ ░░░ ░ ░    ░   ░ ░ ░ ░   ░
  184. // ░  ░  ░   ░              ░       ░
Success #stdin #stdout #stderr 0.01s 5324KB
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stdin
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Standard input is empty
stdout
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-1000000000000000000
stderr
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-------------Time:4.791ms.
3.05218 MB
https://ideone.com/gadErB
language:
C++14 (gcc 8.3)
created:
16 hours ago
visibility:
public

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