Submission #697510

#	Time	Username	Problem	Language	Result	Execution time	Memory
697510		Bobonbush	Discharging (NOI20_discharging)	C++17	72 / 100	114 ms	32200 KiB

Discharging

#include <bits/stdc++.h>
#define foreach for
#define in :
using namespace std;
typedef long long ll ;
const int LOG = 18;
const long long base = 31;
const long long MODULO = 1e9+7;
const long long INF = 1e18+1;
template<class X ,class Y>
    bool Minimize(X &x , Y y)
    {
        if(x > y)
        {
            x = y;
            return true;
        }
        return false;
    }
template<class X , class Y>
    bool Maximize(X &x , Y y)
    {
        if(x < y)
        {
            x = y;
            return true;
        }
        return false;
    }
struct lines
{
    ll a ,b;
    lines(ll _a , ll _b )
    {
        a = _a;
        b = _b;
    }
    ll eval(ll x)
    {
        return a *x + b;
    }
};
deque<lines>adu;


bool bad(lines &l1 , lines &l2 ,lines &l3)
{
    return (l3.b - l1.b) * (l1.a - l2.a) < (l2.b - l1.b) * (l1.a - l3.a);
}
void Add(lines x)
{
    while((int)adu.size() >= 2 && bad( adu[(int)adu.size()-2] , adu[(int)adu.size()-1] , x  ))
    {
        adu.pop_back();
    }
    adu.push_back(x);
}

ll Get(ll x)
{
    while((int)adu.size() >= 2 && adu[0].eval(x) >= adu[1].eval(x)  )adu.pop_front();
    return adu[0].eval(x);
}
const int N = 1e6+1;
int n , a[N];
int _next[N];
long long dp[N];
void Input()
{
    cin >> n ;
    for(int i = 1; i <= n ; i++)
    {
        cin >> a[i];
        if(a[_next[i-1]]  <=  a[i])_next[i] = i;
        else _next[i] = _next[i-1];
    }
}
void Process()
{
    Add(lines(0 , 0));
    for(int i =1 ; i <= n ; i++)
    {
        if(_next[i] != i)dp[i] = dp[i-1];
        else dp[i] = Get(a[i]) + n *1LL * a[i];
        Add(lines( -i * 1LL , dp[i] ));
    }
    cout << dp[n];
}
int main()
{
    ios_base :: sync_with_stdio(0);cin.tie(0);
    int test = 1;
    while(test--)
    {
        Input();
        Process();
    }
    return 0;
}

• Subtask 1: 9 / 9
• Subtask 2: 13 / 13
• Subtask 3: 25 / 25
• Subtask 4: 11 / 11
• Subtask 5: 14 / 14
• Subtask 6: 0 / 28