Submission #1281155

#	Time	Username	Problem	Language	Result	Execution time	Memory
1281155		Shin	Feast (NOI19_feast)	C++20	100 / 100	80 ms	10972 KiB

feast

#include <bits/stdc++.h>

using namespace std;

const int N = 3E5 + 5;

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

signed main() {
    cin.tie(0)->sync_with_stdio(0);
    cin >> n >> k;
    for (int i = 1; i <= n; i++) {
        cin >> a[i];
    }
    auto calc = [&](long long lambda) {
        dp[1][1] = make_pair(a[1] - lambda, 1);
        for (int i = 2; i <= n; i++) {
            dp[i][0] = max(dp[i - 1][0], dp[i - 1][1]);
            auto x = make_pair(dp[i - 1][0].first + a[i] - lambda, dp[i - 1][0].second + 1);
            auto y = make_pair(dp[i - 1][1].first + a[i], dp[i - 1][1].second);
            dp[i][1] = max(x, y);
        }
        return max(dp[n][0], dp[n][1]);
    };
    long long lo = 0;
    long long hi = (long long) 1E18;
    long long res = 0;
    while (lo <= hi) {
        long long mid = lo + (hi - lo) / 2;
        auto [sum, cnt] = calc(mid);
        if (cnt >= k) {
            lo = mid + 1;
            res = mid;
        } else {
            hi = mid - 1;
        }
    }
    auto x = calc(res);
    // cerr << x.first << ' ' << x.second << ' ' << res << '\n';
    cout << x.first + res * k;
    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