Submission #1298041

#TimeUsernameProblemLanguageResultExecution timeMemory
1298041ThunnusDischarging (NOI20_discharging)C++20
100 / 100
91 ms23896 KiB
#include<bits/stdc++.h>
#pragma GCC optimize("unroll-loops,O3")
using namespace std;
using i64 = long long;
#define int i64
#define vi vector<int>
#define vvi vector<vi>
#define vb vector<bool>
#define se second
#define fi first
#define pii pair<int, int>
#define sz(x) (int)(x).size()

struct Line{
    int m, c;
    Line(int m, int c) : m(m), c(c) {}
    Line() : Line(0, 0) {}

    inline int eval(int x){
        return m * x + c;
    }

    inline long double x_int(Line &other){
        return (long double)(other.c - c) / (m - other.m);
    }
};

inline void solve(){
    int n;
    cin >> n;
    vi t(n + 1), pfmax(n + 1);
    for(int i = 1; i <= n; i++){
        cin >> t[i];
        pfmax[i] = max(t[i], pfmax[i - 1]); // nondecreasing
    }

    deque<Line> dq;
    dq.emplace_back(0, 0);
    vi dp(n + 1); // dp[i] = ilk i kişi için olan grupları inceledim finale katkıları: dp[j] + (n - j) * pfmax[i], pfmax'ın o grupta olmadığı durum zaten optimal değil
    for(int i = 1; i <= n; i++){
        while(sz(dq) >= 2 && dq.front().eval(pfmax[i]) >= dq[1].eval(pfmax[i])){
            dq.pop_front();
        }
        dp[i] = n * pfmax[i] + dq.front().eval(pfmax[i]);
        Line line = {-i, dp[i]};
        while(sz(dq) >= 2 && line.x_int(dq.back()) <= dq.back().x_int(dq[sz(dq) - 2])){
            dq.pop_back();
        }
        dq.emplace_back(line);
    }
    cout << dp[n] << "\n";
    return;
}

signed main(){
    ios_base::sync_with_stdio(false); cin.tie(0);
    int t = 1;
    //cin >> t;
    while(t--){
        solve();
    }
    return 0;
}
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