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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. #define ll long long int
  4. const int M = 1e9 + 7;
  5.  
  6. int main()
  7. {
  8.     ios_base::sync_with_stdio(false);
  9.     cin.tie(NULL);
  10.     int n;
  11.     cin >> n;
  12.     vector<int> v(n);
  13.     for (int i = 0; i < n; i++)
  14.         cin >> v[i];
  15.  
  16.     int i = 0;
  17.     int ans = 0;
  18.     while (i < n)
  19.     {
  20.         int st = i, curr = i;
  21.         int dec = 0, inc = 0;
  22.         while (i + 1 < n && v[i + 1] < v[i])
  23.         {
  24.             dec = 1;
  25.             curr++;
  26.             i++;
  27.         }
  28.         if (i + 1 < n && v[i + 1] == v[i])
  29.         {
  30.             i++;
  31.             dec = 0;
  32.             inc = 0;
  33.             continue;
  34.         }
  35.         while (i + 1 < n && v[i + 1] > v[i] && dec == 1)
  36.         {
  37.             inc = 1;
  38.             i++;
  39.         }
  40.         if (inc == 1 && dec == 1)
  41.         {
  42.             ans += (curr - st) * (i - curr);
  43.         }
  44.         else
  45.             i++;
  46.     }
  47.  
  48.     cout << ans << endl;
  49.     return 0;
  50. }
  51.  
Success #stdin #stdout 0s 5316KB
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https://ideone.com/BUFu3L
language:
C++14 (gcc 8.3)
created:
24 days ago
visibility:
public

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