Submission #401993

#	Time	Username	Problem	Language	Result	Execution time	Memory
401993		ronnith	Feast (NOI19_feast)	C++14	100 / 100	202 ms	11516 KiB

feast

#include <bits/stdc++.h>

using namespace std;

const int N = (int)3e5, K = (int)3e5;
int n, k;
int a[N];
int64_t dp[N][2];
int cnt[N][2];

int main() {
	ios_base::sync_with_stdio(false);
	cin.tie(nullptr);

	cin >> n >> k;
	for (int i = 0;i < n;i ++)
		cin >> a[i];

	auto check = [&](int64_t penalty) -> pair<int, int64_t> {
		for (int i = 0;i < n;i ++) {
			for (int pr = 0;pr < 2;pr ++) {
				dp[i][pr] = LLONG_MIN;
				cnt[i][pr] = INT_MAX;
			}
		}

		if (0 >= a[0] - penalty) {
			dp[0][0] = 0;
			cnt[0][0] = 0;
		} else {
			dp[0][0] = a[0] - penalty;
			cnt[0][0] = 1;
		}

		dp[0][1] = a[0] - penalty;
		cnt[0][1] = 1;
		for (int i = 1;i < n;i ++) {
			if (dp[i - 1][0] + a[i] - penalty > dp[i][0] || (dp[i - 1][0] + a[i] - penalty == dp[i][0] && cnt[i - 1][0] + 1 < cnt[i][0])) {
				dp[i][0] = dp[i - 1][0] + a[i] - penalty;
				cnt[i][0] = cnt[i - 1][0] + 1;
			}

			if (dp[i - 1][0] > dp[i][0] || (dp[i - 1][0] == dp[i][0] && cnt[i - 1][0] < cnt[i][0])) {
				dp[i][0] = dp[i - 1][0];
				cnt[i][0] = cnt[i - 1][0];
			}

			if (dp[i - 1][1] + a[i] > dp[i][0] || (dp[i - 1][1] + a[i] == dp[i][0] && cnt[i - 1][1] < cnt[i][0])) {
				dp[i][0] = dp[i - 1][1] + a[i];
				cnt[i][0] = cnt[i - 1][1];
			}

			if (dp[i - 1][1] + a[i] > dp[i][1] || (dp[i - 1][1] + a[i] == dp[i][1] && cnt[i - 1][1] < cnt[i][1])) {
				dp[i][1] = dp[i - 1][1] + a[i];
				cnt[i][1] = cnt[i - 1][1];
			}

			if (dp[i - 1][0] + a[i] - penalty > dp[i][1] || (dp[i - 1][0] + a[i] - penalty == dp[i][1] && cnt[i - 1][0] + 1 < cnt[i][1])) {
				dp[i][1] = dp[i - 1][0] + a[i] - penalty;
				cnt[i][1] = cnt[i - 1][0] + 1;
			}
		}

		return {cnt[n - 1][0], dp[n - 1][0]};
	};

	int64_t lx = 0, rx = (int64_t)1e15;

	while (lx < rx) {
		int64_t g = lx + (rx - lx) / 2;
		if (check(g).first <= k)
			rx = g;
		else
			lx = g + 1;
	}


	pair<int, int64_t> res = check(lx);
	int64_t ans = res.second + (k - res.first) * lx + lx * k;

	cout << ans << '\n';

	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