Submission #545010

#	Time	Username	Problem	Language	Result	Execution time	Memory
545010		pure_mem	Feast (NOI19_feast)	C++14	100 / 100	705 ms	24588 KiB

feast

#include <bits/stdc++.h>

#define ll long long
#define ld long double
#define X first
#define Y second
#define MP make_pair

using namespace std;

const int N = 3e5 + 12;

int n, k; 
ll a[N];
pair<ld, int> dp[N][2];

void prints(pair<ld, int> x) {
	cerr << x.X << " " << x.Y;
}

pair<ld, int> get(ld m, bool debug = 0) {
	dp[1][0] = {0, 0};
	dp[1][1] = {a[1] - m, 1};
	for(int i = 2;i <= n;i++) {
		dp[i][0] = max(dp[i - 1][0], dp[i - 1][1]);
		dp[i][1] = max(MP(dp[i - 1][0].X + a[i] - m, dp[i - 1][0].Y + 1), 
					   MP(dp[i - 1][1].X + a[i], dp[i - 1][1].Y));	
		if(debug) {
			prints(dp[i][0]), cerr << " | ", prints(dp[i][1]);
			cerr << "\n";
		}
	}	
	return max(dp[n][0], dp[n][1]);
}

int main () {
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
 	
	cin >> n >> k;
	for(int i = 1;i <= n;i++)
		cin >> a[i];

	ld l = 0, r = 1e15;
	for(int it = 0;it < 100;it++) {
		ld m = (l + r) / 2;
		auto mid = get(m);
		if(mid.Y >= k) {
			l = m;
		} 	
		else {
			r = m;
		}
		
	}
	
	auto mid = get(l);      
	ll answer = round(mid.X + l * k);
	cout << answer;
}

• 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