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  1. #include <bits/stdc++.h>
  2.  
  3. #define ll long long
  4. #define el cout << '\n'
  5.  
  6. using namespace std;
  7.  
  8. const int maxn = 1e7;
  9. const int INF = 1e9;
  10.  
  11. int n, a[maxn + 10], l[maxn + 10], r[maxn + 10], cnt[maxn + 10], mx = 0, j = maxn, ans;
  12. vector<int> stk, pos[maxn + 10];
  13.  
  14. void update()
  15. {
  16.     while (cnt[j] == 0)
  17.         j--;
  18. }
  19.  
  20. int main()
  21. {
  22.     ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
  23.     if (fopen("QUANTIEUPHU.INP", "r"))
  24.     {
  25.         freopen("QUANTIEUPHU.INP", "r", stdin);
  26.         freopen("QUANTIEUPHU.OUT", "w", stdout);
  27.     }
  28.  
  29.     cin >> n;
  30.     for (int i = 1; i <= n; i++)
  31.     {
  32.         cin >> a[i];
  33.         pos[a[i]].push_back(i);
  34.         mx = max(mx, a[i]);
  35.     }
  36.     a[0] = a[n + 1] = INF;
  37.     stk.push_back(0);
  38.  
  39.     for (int i = 1; i <= n; i++)
  40.     {
  41.         while (a[i] > a[stk.back()])
  42.             stk.pop_back();
  43.         l[i] = stk.back();
  44.         stk.push_back(i);
  45.     }
  46.     stk.clear();
  47.     stk.push_back(n + 1);
  48.     for (int i = n; i >= 1; i--)
  49.     {
  50.         while (a[i] >= a[stk.back()])
  51.             stk.pop_back();
  52.         r[i] = stk.back();
  53.         stk.push_back(i);
  54.     }
  55.     for (int x : pos[mx])
  56.         cnt[x - l[x]]++;
  57.     for (int i = mx - 1; i >= 0; i--)
  58.     {
  59.         for (int x : pos[i])
  60.         {
  61.             cnt[r[x] - l[x]]--;
  62.             cnt[x - l[x]]++;
  63.             cnt[r[x] - x]++;
  64.         }
  65.         update();
  66.         if (j <= i)
  67.             ans = j;
  68.     }
  69.     cout << ans;
  70. }
  71.  
Success #stdin #stdout 0.05s 240764KB
comments (?)
stdin 
Standard input is empty
stdout 
Standard output is empty
https://ideone.com/MtRAdp
language:
C++14 (gcc 8.3)
created:
1 day ago
visibility:
public

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