Submission #1103042

#	Time	Username	Problem	Language	Result	Execution time	Memory
1103042		rastervc	Feast (NOI19_feast)	C++17	100 / 100	140 ms	14084 KiB

feast

#include <iostream>

constexpr long long INF = 1e18;
constexpr int MAX_N = 3e5 + 5;
int N, K, a[MAX_N];
std::pair<long long, int> dp[MAX_N][2];

std::pair<long long, int> check(long long lambda) {
    dp[1][0] = { 0, 0 };
    dp[1][1] = { a[1] - lambda, 1 };

    for (int i = 2; i <= N; ++i) {
        dp[i][0] = std::max(dp[i - 1][0], dp[i - 1][1]);
        dp[i][1] = std::max(
            std::make_pair(dp[i - 1][0].first + a[i] - lambda, dp[i - 1][0].second + 1),
            std::make_pair(dp[i - 1][1].first + a[i], dp[i - 1][1].second)
        );
    }

    return std::max(dp[N][0], dp[N][1]);
}

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

    std::cin >> N >> K;
    for (int i = 1; i <= N; ++i)
        std::cin >> a[i];
    
    long long l = 0, r = INF, ans = 0;
    while (l < r) {
        long long mid = (l + r + 1) >> 1;
        if (check(mid).second >= K) l = mid;
        else r = mid - 1;
    }

    std::cout << check(l).first + l * K;

    return 0;
}

Compilation message (stderr)

feast.cpp: In function 'int main()':
feast.cpp:31:31: warning: unused variable 'ans' [-Wunused-variable]
   31 |     long long l = 0, r = INF, ans = 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