Submission #923779

#	Time	Username	Problem	Language	Result	Execution time	Memory
923779		Karoot	Feast (NOI19_feast)	C++17	100 / 100	261 ms	25180 KiB

feast

#pragma GCC optimize("Ofast,inline") 
#pragma GCC optimize ("unroll-loops")

#include <iostream>
#include <cmath>
#include <unordered_map>
#include <map>
#include <set>
#include <queue>
#include <vector>
#include <string>
#include <iomanip>
#include <algorithm>
#include <chrono>

#define all(x)  (x).begin(), (x).end()
#define rall(x)  (x).rbegin(), (x).rend()

using namespace std;

typedef long long ll;

ll linf = 1e15+1;

inline void scoobydoobydoo(){
    ios::sync_with_stdio(false);
    ios_base::sync_with_stdio(false);
    cin.tie(NULL); cout.tie(NULL);
}

const int MAXN = 3e5+3;
ll arr[MAXN];
pair<long double, ll> mem[MAXN][2];
ll n, k; 
bool isVisited[MAXN][2];

long double lambda;

pair<long double, ll> dp(){
    mem[0][0] = {0, 0};
    mem[0][1] = {arr[0]-lambda, 1};
    for (int i = 1; i < n; i++){
        // 0
        mem[i][0] = max(mem[i-1][0], mem[i-1][1]);

        //buy from 0, continue 1

        mem[i][1] = max(make_pair(mem[i-1][0].first+arr[i]-lambda, mem[i-1][0].second+1), make_pair(mem[i-1][1].first+arr[i], mem[i-1][1].second));
    }
    return max(mem[n-1][0], mem[n-1][1]);
}

bool check(long double la){
    lambda = la;
    for (int i = 0; i < n; i++){
        isVisited[i][0] = false;
        isVisited[i][1] = false;
    }
    //cout << la << " " << dp(0, 0).first << " " << dp(0, 0).second << endl;
    return dp().second >= k; 
}

int main(){
    scoobydoobydoo();
    cin >> n >> k;
    for (int i = 0; i < n; i++)cin >> arr[i];

    long double b = 0;
    for (int i = 0; i < n; i++)b += abs(arr[i]);

    long double a = 0;

    chrono::time_point<chrono::system_clock> start, end;

    start = chrono::system_clock::now();

    while (a+(1e-3) < b){
        long double mid = (a+b)/2.0;
        if (check(mid)){
            a = mid;
        } else {
            b = mid;
        }
        end = chrono::system_clock::now();
        chrono::duration<double> elapsed_seconds = end - start;
        if (elapsed_seconds.count() > 0.9)break;
    }

    check(a);

    ll ans = round(a*k + max(mem[n-1][0], mem[n-1][1]).first);
    
    cout << ans << endl;


    return 0;
}

• Subtask 1: 4 / 4
• Subtask 2: 8 / 8
• Subtask 3: 18 / 18
• Subtask 4: 10 / 10
• Subtask 5: 11 / 11
• Subtask 6: 20 / 20
• Subtask 7: 29 / 29