题解

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

int main() {
	int n, k;
	cin >> n >> k;
	vector<int> skill(n);
	for (int i = 0; i < n; i++) { cin >> skill[i]; }

	vector<int> dp(n, -1);
	for (int i = 0; i < n; i++) {
		int cur = skill[i];
		for (int j = i; j >= (i - k + 1) && ~j; j--) {
			cur = max(cur, skill[j]);
			if (j > 0) {
				dp[i] = max(dp[i], dp[j - 1] + (cur * (i - j + 1)));
			} else {
				dp[i] = max(dp[i], cur * (i - j + 1));
			}
		}
	}
	cout << dp[n - 1] << endl;
}