Submission #817418

#	Time	Username	Problem	Language	Result	Execution time	Memory
817418		vjudge1	Feast (NOI19_feast)	C++17	40 / 100	248 ms	14616 KiB

feast

#include <bits/stdc++.h>
using namespace std;

void main_program();

signed main(){
	ios_base::sync_with_stdio(0); cin.tie(0);
	main_program();
}

#define int long long

using ii = pair<int, int>;

int n, k;
vector<int> v, pfx;

ii better(ii a, ii b){
	if (a.first != b.first){
		return (a.first > b.first) ? a : b;
	}
	return (a.second < b.second) ? a : b;
}

ii f(int lambda){
	vector<ii> dp_closed(n), dp_open(n);
	dp_closed[0] = {0, 0};
	dp_open[0] = {max(0LL, -pfx[0]), 0};

	for (int i = 1; i < n; i++){
		dp_closed[i] = better(dp_closed[i-1],
			{dp_open[i-1].first + pfx[i] - lambda, dp_open[i-1].second + 1});
		dp_open[i] = better(dp_open[i-1],
			{dp_closed[i-1].first - pfx[i], dp_closed[i-1].second});
	}

	return dp_closed[n-1];
}

void main_program(){
	cin >> n >> k;

	v.resize(n);
	for (int i = 0; i < n; i++) cin >> v[i];
	pfx = v;
	for (int i = 1; i < n; i++) pfx[i] += pfx[i-1];

	int l = 0, r = 3e14;
	ii final = {(int)-1e18, 0LL};
	while (l <= r){
		int mid = (l + r) >> 1;
		auto res = f(mid);
		if (res.second <= k){
			r = mid - 1;
			final = res;
		}
		else l = mid + 1;
	}

	cout << final.first + l * final.second << "\n";
}

• Subtask 1: 4 / 4
• Subtask 2: 8 / 8
• Subtask 3: 18 / 18
• Subtask 4: 10 / 10
• Subtask 5: 0 / 11
• Subtask 6: 0 / 20
• Subtask 7: 0 / 29