Submission #1104094

#	Time	Username	Problem	Language	Result	Execution time	Memory
1104094		ridarfx	Feast (NOI19_feast)	C++14	100 / 100	212 ms	12580 KiB

feast

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

#define ll long long

int main() {
	int n, k;
	cin >> n >> k;
    long long rk = 0;
	int a[n];
	for (int &i : a) { cin >> i;}
	/**
	 * @return the maximum sum along with the number of subarrays used
	 * if creating a subarray penalizes the sum by "lmb" and
	 * there is no limit to the number of subarrays you can create
	 */
	auto solve_lambda = [&](ll lmb) {
		pair<ll, ll> dp[n][2];

		dp[0][0] = {0, 0};
		dp[0][1] = {a[0] - lmb, 1};

		for (int i = 1; i < n; i++) {
			dp[i][0] = max(dp[i - 1][0], dp[i - 1][1]);

			dp[i][1] =
			    max(make_pair(dp[i - 1][0].first + a[i] - lmb, dp[i - 1][0].second + 1),
			        make_pair(dp[i - 1][1].first + a[i], dp[i - 1][1].second));
		}

		return max(dp[n - 1][0], dp[n - 1][1]);
	};

	ll lo = 0;
	ll hi = 1e18;
	while (lo < hi) {
		ll mid = (lo + hi + 1) / 2;
		solve_lambda(mid).second >= k ? lo = mid : hi = mid - 1;
	}

	cout << solve_lambda(lo).first + lo * k << endl;
}

Compilation message (stderr)

feast.cpp: In function 'int main()':
feast.cpp:9:15: warning: unused variable 'rk' [-Wunused-variable]
    9 |     long long rk = 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