Submission #1269774

#	Time	Username	Problem	Language	Result	Execution time	Memory
1269774		ducdev	Feast (NOI19_feast)	C++17	59 / 100	1096 ms	10848 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

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();
};

Compilation message (stderr)

feast.cpp: In function 'int main()':
feast.cpp:54:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   54 |         freopen("MAIN.INP", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
feast.cpp:55:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   55 |         freopen("MAIN.OUT", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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