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  1. #include<bits/stdc++.h>
  2. #define ull unsigned long long
  3. #define ll long long
  4. #define all(x) x.begin(), x.end()
  5. using namespace std;
  6. const int maxn = 1e5 + 1;
  7. ll A[3001][3001];
  8. map<pair<int, int>, int> mp;
  9. int main() {
  10.     ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
  11.     int n;
  12.     ll x;
  13.     cin >> n;
  14.     for (int i = 1; i <= n; ++i) {
  15.         cin >> x;
  16.         A[0][i] = x;
  17.         A[n - i + 1][0] = x;
  18.     }
  19.     for (int i = 1; i <= n; ++i) {
  20.         for (int j = 1; j <= n; ++j) {
  21.             A[i][j] = A[0][j] * A[i][0];
  22.         }
  23.     }
  24.     int j = n;
  25.     for (int i = 1; i <= n; ++i) {
  26.         mp[make_pair(i, j)] = true;
  27.         --j;
  28.     }
  29.     ll res = INT_MIN;
  30.     for (int i = 1; i < n; ++i) {
  31.         for (int j = 1; j < n; ++j) {
  32.             int fakeI = i, fakeJ = j;
  33.             ll sum = 0;
  34.             while (mp[make_pair(fakeI, fakeJ)] == false && fakeI < n && fakeJ < n) {
  35.                 sum += A[fakeI][fakeJ];
  36.                 ++fakeI;
  37.                 ++fakeJ;
  38.             }
  39.             res = max(res, sum);
  40.         }
  41.     }
  42.     cout<<res;
  43. }
  44.  
Success #stdin #stdout 0.01s 5284KB
comments (?)
stdin 
5 
3 2 -9 1 -8
stdout 
72
https://ideone.com/8KbuDX
language:
C++14 (gcc 8.3)
created:
3 days ago
visibility:
public

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