Submission #1300132

#	Time	Username	Problem	Language	Result	Execution time	Memory
1300132		nathan4690	Discharging (NOI20_discharging)	C++20	100 / 100	78 ms	18376 KiB

Discharging

#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define f1(i,n) for(int i=1;i<=n;i++)
#define __file_name "TEST"
using namespace std;
const ll maxn=1e6+5, inf=1e18;

struct Line{
    ll a, b;
    bool operator<(const Line &rhs) const{
        return make_pair(a, -b) < make_pair(rhs.a, -rhs.b);
    }
};

bool check(Line l1, Line l2, Line l3){
    return 1.0L * (l2.b - l1.b) / (l2.a - l1.a) >= 1.0L * (l3.b - l2.b) / (l3.a - l2.a);
}

deque<Line> S;

void addLine(Line l){
    while(S.size() > 1){
        if(check(S[S.size() - 2], S.back(), l)) S.pop_back();
        else break;
    }
    S.push_back(l);
}

ll n, t[maxn], dp[maxn];
vector<ll> a;

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    if(fopen(__file_name ".inp", "r")){
        freopen(__file_name ".inp", "r", stdin);
        freopen(__file_name ".out", "w", stdout);
    }
    // code here
    cin >> n;
    f1(i,n) cin >> t[i];
    t[n + 1] = inf;
    a.push_back(n + 1);
    for(int i = n; i >= 1; i--){
        while(t[a.back()] <= t[i]){
            a.pop_back();
        }
        a.push_back(i);
    }
    reverse(a.begin(), a.end());
    a.pop_back();
    int sz = a.size();
    a.insert(a.begin(), 0);
//    for(int i: a) cout << i << ' ';
//    cout << '\n';
    f1(i,sz){
        Line l1;
        l1.a = a[i];
        l1.b = dp[i-1];
        addLine(l1);
        ll val = -t[a[i]];
        while(S.size() > 1){
            Line la = S.front();
            S.pop_front();
            Line lb = S.front();
            if(la.a * (val) + la.b < lb.a * (val) + lb.b){
                S.push_front(la);
                break;
            }
        }
        dp[i] = (-val) * (n + 1) + S.front().a * (val) + S.front().b;
    }
//    cout << dp[2] << '\n';
    cout << dp[sz];
    return 0;
}

Compilation message (stderr)

Discharging.cpp: In function 'int main()':
Discharging.cpp:37:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   37 |         freopen(__file_name ".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Discharging.cpp:38:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   38 |         freopen(__file_name ".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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