Submission #1043400

#	Time	Username	Problem	Language	Result	Execution time	Memory
1043400		vjudge1	Discharging (NOI20_discharging)	C++17	100 / 100	73 ms	16100 KiB

Discharging

#include <bits/stdc++.h>

using namespace std;
using ll = long long;

#define int long long
#define FOR(i, a, b) for (int i = (a); i <= (b); i++)
#define FORD(i, a, b) for (int i = (b); i >= (a); i --)
#define REP(i, a) for (int i = 0; i < (a); ++i)
#define REPD(i, a) for (int i = (a) - 1; i >= 0; --i)

#define MASK(i) (1LL << (i))
#define BIT(x, i) (((x) >> (i)) & 1)


constexpr ll LINF = (1ll << 60);
constexpr int INF = (1ll << 30);
constexpr int Mod = 1e9 + 7;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

/*
    Phu Trong from Nguyen Tat Thanh High School for gifted student
*/

template <class X, class Y>
    bool minimize(X &x, const Y &y){
        X eps = 1e-9;
        if (x > y + eps) {x = y; return 1;}
        return 0;
    }

template <class X, class Y>
    bool maximize(X &x, const Y &y){
        X eps = 1e-9;
        if (x + eps < y) {x = y; return 1;}
        return 0;
    }
#define MAX             1000005
int nArr;

int dp[MAX], A[MAX];
struct Line{
    int a, b;
    Line(int _a = 0, int _b = LINF): a(_a), b(_b){}

    double cross(Line o){
        return (double)(o.b - b) / (double)(a - o.a);
    }
    int f(int x){return a * x + b;}
};

struct CHT{
    deque<Line> q;
    CHT(){}
    void clear(void){
        q.clear();
    }
    bool bad(Line a, Line b, Line c){
        return a.cross(c) <= a.cross(b);
    }
    void addLine(Line line){
        while(q.size() >= 2 && bad(q.end()[-2], q.end()[-1], line))
            q.pop_back();
        q.push_back(line);
    }
    void addLine(int a, int b){
        addLine(Line(a, b));
    }

    int query(int x){
        while(q.size() >= 2 && q[0].f(x) >= q[1].f(x)){
            q.pop_front();
        }
        return q[0].f(x);
    }
};

//slope decreasing, query increasing

void process(void){
    cin >> nArr;
    for (int i = 1; i <= nArr; ++i) {
        cin >> A[i];
        maximize(A[i], A[i - 1]);
    }

    memset(dp, 0x3f, sizeof dp);
    dp[0] = 0;
    CHT cht;
    cht.addLine(0, 0);
    FOR(i, 1, nArr){
        dp[i] = cht.query(A[i]) + A[i] * nArr;
        cht.addLine(-i, dp[i]);
    }
    cout << dp[nArr];
}
signed main(){
    #define name "Whisper"
    cin.tie(nullptr) -> sync_with_stdio(false);
    //freopen(name".inp", "r", stdin);
    //freopen(name".out", "w", stdout);
    process();
    return (0 ^ 0);
}

• Subtask 1: 9 / 9
• Subtask 2: 13 / 13
• Subtask 3: 25 / 25
• Subtask 4: 11 / 11
• Subtask 5: 14 / 14
• Subtask 6: 28 / 28