Submission #1270086

#	Time	Username	Problem	Language	Result	Execution time	Memory
1270086		ducdev	Feast (NOI19_feast)	C++17	30 / 100	75 ms	8592 KiB

feast

// Author: 4uckd3v - Nguyen Cao Duc
#include <bits/stdc++.h>
using namespace std;

typedef long long ll;

const int MAX_N = 1e6;
const int MOD = 1e9 + 7;
const ll INF = 1e18;

int n, k;
int a[MAX_N + 5];
ll pref[MAX_N + 5];

ll getSum(int l, int r) {
    return pref[r] - pref[l - 1];
};

namespace SUBTASK_3456 {
    const int LIM = 1e8;

    bool checkSubtask() {
        return 1LL * n * k <= LIM;
    };

    void Solve() {
        vector<ll> cur(n + 5, -INF), nxt(n + 5, -INF), mx(n + 5);

        for (int i = 0; i <= n; i++) cur[i] = 0;

        nxt[0] = 0;
        ll res = 0;
        for (int i = 1; i <= k; i++) {
            mx[i - 1] = -INF;
            for (int r = i; r <= n; r++) {
                mx[r] = max(mx[r - 1], cur[r - 1] - pref[r - 1]);
                nxt[r] = max(nxt[r - 1], mx[r] + pref[r]);
            };
            for (int r = i; r <= n; r++) {
                cur[r] = nxt[r];
                nxt[r] = -INF;
            };
            res = max(res, cur[n]);
        };

        cout << res << '\n';
    };
};  // namespace SUBTASK_3456

namespace SUBTASK_7 {
    const int N = MAX_N;

    pair<ll, int> dp[N + 5];

    pair<ll, int> calc(ll lambda) {
        for (int i = 0; i <= n; i++) dp[i] = {0, 0};

        pair<ll, int> mx = {0, 0};

        dp[0] = {0, 0};
        for (int i = 1; i <= n; i++) {
            if (dp[i - 1].first - pref[i - 1] > mx.first)
                mx = {dp[i - 1].first - pref[i - 1], dp[i - 1].second};
            else if (dp[i - 1].first - pref[i - 1] == mx.first)
                mx = {dp[i - 1].first - pref[i - 1], min(mx.second, dp[i - 1].second)};

            if (dp[i - 1].first > mx.first + pref[i] - lambda) {
                dp[i] = dp[i - 1];
            } else if (dp[i - 1].first == mx.first + pref[i] - lambda) {
                dp[i].first = mx.first + pref[i];
                dp[i].second = min(dp[i - 1].second, mx.second + 1);
            } else {
                dp[i].first = mx.first + pref[i] - lambda;
                dp[i].second++;
            };
        };

        return dp[n];
    };

    void Solve() {
        ll l = -3e14, r = 3e14, lambda = 0;

        while (l <= r) {
            ll mid = l + (r - l) / 2;
            if (calc(mid).second >= k) {
                lambda = mid;
                l = mid + 1;
            } else
                r = mid - 1;
        };

        cout << calc(lambda).first + lambda * k << '\n';
    };
};  // namespace SUBTASK_7

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    if (fopen("MAIN.INP", "r")) {
        freopen("MAIN.INP", "r", stdin);
        freopen("MAIN.OUT", "w", stdout);
    };

    cin >> n >> k;
    for (int i = 1; i <= n; i++) {
        cin >> a[i];
        pref[i] = pref[i - 1] + a[i];
    };

    // SUBTASK_3456::Solve();
    SUBTASK_7::Solve();
};

Compilation message (stderr)

feast.cpp: In function 'int main()':
feast.cpp:101:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  101 |         freopen("MAIN.INP", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
feast.cpp:102:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  102 |         freopen("MAIN.OUT", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 4 / 4
• Subtask 2: 8 / 8
• Subtask 3: 18 / 18
• Subtask 4: 0 / 10
• Subtask 5: 0 / 11
• Subtask 6: 0 / 20
• Subtask 7: 0 / 29