This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include<bits/stdc++.h>
#pragma GCC optimize("Ofast")
#pragma GCC target("avx2,fma")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#pragma GCC optimization ("O3")
#pragma GCC optimization ("unroll-loops")
#define ll long long
#define f first
#define s second
#define pb push_back
using namespace std;
int n,a[1000002];
ll dp[1000002];
int rm[1000002][21],po[2000002],pw[200],raod,mn,lo,pr[2000002];
int lef[1000002],rig[1000002];
vector<int>del[1000002];
int get(int x,int y){
    return pr[y];
}
int ind(int x,int y){
    if(y == n)return -1;
    ll l = y + 1,r = n,mid,ind = -1;
    while(r >= l){
        mid = (l + r) / 2;
        if(dp[x] + (ll)get(x + 1 , mid) * (n - x) > dp[y] + (ll)get(y + 1 , mid) * (n - y)){
            r = mid - 1;
            ind = mid;
        }
        else
            l = mid + 1;
    }
    return ind;
}
void delet(int x){
    if(lef[x] == rig[x] && lef[x] == -1)return;
    if(lef[x] == -1){
        lef[rig[x]] = -1;
        mn = rig[x];
        rig[x] = -1;
        return;
    }
    rig[lef[x]] = rig[x];
    lef[rig[x]] = lef[x];
    int cur = ind(lef[x] , rig[x]);
    if(cur == -1){
        lef[x] = rig[x] = -1;
        return;
    }
    del[cur].pb(lef[x]);
    lef[x] = rig[x] = -1;
}
int main(){
    scanf("%d",&n);
    for(int i=1; i<=n; i++){
        scanf("%d",&a[i]);
        pr[i] = max(a[i] , pr[i - 1]);
    }
    for(int i=0; i<=n; i++)
        lef[i] = rig[i] = -1;
    for(int i=1; i<=n; i++){
        for(int j=0; j<del[i].size(); j++){
            delet(del[i][j]);
        }
        dp[i] = dp[mn] + (ll)get(mn + 1 , i) * (ll)(n - mn);
        rig[i - 1] = i;
        lef[i] = i - 1;
        ll cur = ind(i - 1 , i);
        if(cur != -1)
            del[cur].pb(i - 1);
    }
    //cout << "time: " << clock() - cl << " " << raod << '\n';
    cout << dp[n];
    
    
    return 0;
}
Compilation message (stderr)
Discharging.cpp:5: warning: ignoring #pragma GCC optimization [-Wunknown-pragmas]
    5 | #pragma GCC optimization ("O3")
      | 
Discharging.cpp:6: warning: ignoring #pragma GCC optimization [-Wunknown-pragmas]
    6 | #pragma GCC optimization ("unroll-loops")
      | 
Discharging.cpp: In function 'int main()':
Discharging.cpp:61:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   61 |         for(int j=0; j<del[i].size(); j++){
      |                      ~^~~~~~~~~~~~~~
Discharging.cpp:53:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   53 |     scanf("%d",&n);
      |     ~~~~~^~~~~~~~~
Discharging.cpp:55:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   55 |         scanf("%d",&a[i]);
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