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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. #define ll long long
  4. #define pb push_back
  5. #define fi first
  6. #define se second
  7.  
  8. int main() {
  9.     ios_base::sync_with_stdio(0);
  10.     cin.tie(0); cout.tie(0);
  11.  
  12.     int n; cin >> n;
  13.     vector<pair<ll,ll>> a;
  14.     for(int i = 1; i <= n; i++){
  15.         ll x; cin >> x;
  16.         if(a.empty())
  17.             a.pb({x, 1});
  18.         else if(x == a.back().fi)
  19.             a.back().se++;
  20.         else a.pb({x, 1});
  21.     }
  22.  
  23.     ll ans = 0;
  24.     for(auto v : a) 
  25.         ans += (v.se * (v.se - 1)) / 2;
  26.  
  27.     if(a.size() < 2){
  28.         cout << ans;
  29.         return 0;
  30.     }
  31.  
  32.     ll sum_prev = a[0].se;
  33.  
  34.     for(int i = 1; i < a.size(); i++){
  35.         if(i >= 2){
  36.             if((a[i].fi > a[i - 1].fi) == (a[i - 1].fi > a[i - 2].fi)){
  37.                 sum_prev = a[i - 1].se;
  38.             }
  39.         }
  40.         ans += a[i].se * sum_prev;
  41.         sum_prev += a[i].se;
  42.     }
  43.  
  44.     cout << ans;
  45.     return 0;
  46. }
Success #stdin #stdout 0s 5320KB
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239640778
https://ideone.com/qRyjHq
language:
C++ (gcc 8.3)
created:
1 day ago
visibility:
public

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