Submission #949759

#	Time	Username	Problem	Language	Result	Execution time	Memory
949759		steveonalex	Discharging (NOI20_discharging)	C++14	100 / 100	87 ms	22612 KiB

Discharging

#include <bits/stdc++.h>
using namespace std;
 
typedef long long ll;
typedef unsigned long long ull;
 
#define MASK(i) (1ULL << (i))
#define GETBIT(mask, i) (((mask) >> (i)) & 1)
#define ALL(v) (v).begin(), (v).end()
 
ll max(ll a, ll b){return (a > b) ? a : b;}
ll min(ll a, ll b){return (a < b) ? a : b;}
 
ll LASTBIT(ll mask){return (mask) & (-mask);}
int pop_cnt(ll mask){return __builtin_popcountll(mask);}
int ctz(ull mask){return __builtin_ctzll(mask);}
int logOf(ull mask){return 63 - __builtin_clzll(mask);}
 
// mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
mt19937_64 rng(69);
ll rngesus(ll l, ll r){return l + (ull) rng() % (r - l + 1);}
 
template <class T1, class T2>
    bool maximize(T1 &a, T2 b){
        if (a < b) {a = b; return true;}
        return false;
    }
 
template <class T1, class T2>
    bool minimize(T1 &a, T2 b){
        if (a > b) {a = b; return true;}
        return false;
    }
 
template <class T>
    void printArr(T& container, string separator = " ", string finish = "\n", ostream &out = cout){
        for(auto item: container) out << item << separator;
        out << finish;
    }
 
template <class T>
    void remove_dup(vector<T> &a){
        sort(ALL(a));
        a.resize(unique(ALL(a)) - a.begin());
    }

const int N = 1e6 + 69;
const ll INF = 1e18 + 69;
int n;
ll a[N];
ll dp[N];

namespace Sub2{
    void solve(){
        reverse(a + 1, a + n + 1);
        memset(dp, 63, sizeof dp);
        dp[0] = 0;
        for(int i = 1; i<=n; ++i){
            ll ma = 0;
            for(int j = i; j>=1; --j){
                maximize(ma, a[j]);
                minimize(dp[i], dp[j-1] + 1LL * ma * i);
            }
        }

        cout << dp[n] << "\n";
        exit(0);
    }
}
namespace Sub4{
    bool check(){
        for(int i = 1; i<n; ++i) if (a[i] < a[i+1]) return false;
        return true;
    }

    void solve(){
        cout << a[1] * n << "\n";
        exit(0);
    }
}

namespace Sub6{
    struct CHT{
        #define Line pair<ll, ll>

        vector<Line> a;
        vector<double> bubble;

        CHT(){
        }

        double get_intersection(Line a, Line b){
            return (double) (b.second - a.second) / (a.first - b.first);
        }

        void add(Line f){
            if (a.size() && a.back().first == f.first) return;
            if (a.empty()) {a.push_back(f); return;}
            while(bubble.size()){
                double x = bubble.back(), y = get_intersection(a.back(), f);
                if (x >= y){
                    a.pop_back(); bubble.pop_back();
                }
                else break;
            }
            bubble.push_back(get_intersection(a.back(), f));
            a.push_back(f);
        }

        ll get(ll x){
            int idx = lower_bound(ALL(bubble), x) - bubble.begin();
            return a[idx].first * x + a[idx].second;
        }
    };

    void solve(){
        reverse(a + 1, a + n + 1);
        CHT hull_min;
        memset(dp, 63, sizeof dp);
        dp[0] = 0;
        for(int i = n-1; i>=1; --i) maximize(a[i], a[i+1]);
        for(int i = 1; i<=n; ++i){
            hull_min.add(make_pair(a[i], dp[i-1]));
            dp[i] = hull_min.get(i);
        }

        cout << dp[n] << "\n";

        exit(0);
    }
}

int main(void){
    ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);

    cin >> n;
    for(int i= 1; i<=n; ++i) cin >> a[i];

    Sub6::solve();

    return 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