Submission #1062469

#	Time	Username	Problem	Language	Result	Execution time	Memory
1062469		CodeLakVN	Feast (NOI19_feast)	C++17	71 / 100	38 ms	64240 KiB

feast

#include <bits/stdc++.h>

#define no "NO"
#define yes "YES"
#define F first
#define S second
#define vec vector
#define task "FEAST"
#define ll long long
#define _mp make_pair
#define ii pair<int, int>
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define evoid(val) return void(std::cout << val)
#define FOR(i, a, b) for(int i = (a); i <= (b); ++i)
#define FOD(i, b, a) for(int i = (b); i >= (a); --i)
#define unq(x) sort(all(x)); x.resize(unique(all(x)) - x.begin())

using namespace std;

template<typename U, typename V> bool maximize(U &a, V b) {
    if (a < b) { a = b; return 1; } return 0;
}
template<typename U, typename V> bool minimize(U &a, V b) {
    if (a > b) { a = b; return 1; } return 0;
}

const int N = (int)3e5 + 9;
const int INF = (int)1e9;
const int MOD = (int)1e9 + 7;

int n, k;
int a[N];

namespace sub3 {
    bool valid() {
        return k == 1;
    }

    void solve() {
        ll sum = 0, minPre = 0, ans = 0;
        FOR(i, 1, n) {
            sum += a[i];
            maximize(ans, sum - minPre);
            minimize(minPre, sum);
        }
        cout << ans << "\n";
    }
}

namespace sub1 {
    bool valid() {
        return *min_element(a + 1, a + n + 1) >= 0;
    }

    void solve() {
        ll ans = 0;
        FOR(i, 1, n) ans += a[i];
        cout << ans << "\n";
    }
}

namespace sub2 {
    bool valid() {
        bool appeared = 0;
        FOR(i, 1, n) {
            if (a[i] < 0 && appeared) return false;
            if (a[i] < 0) appeared = 1;
        }
        return true;
    }

    void solve() {
        ll ans = 0;
        FOR(i, 1, n) ans += a[i];
        ans -= *min_element(a + 1, a + n + 1);
        cout << ans << "\n";
    }
}

namespace sub5 {
    const int N = 303;
    ll dp[N][N];
    ll sum[N];

    bool valid() {
        return n <= 300;
    }

    void solve() {
        FOR(i, 1, n) sum[i] = sum[i - 1] + a[i];

        memset(dp, -0x3f, sizeof(dp));
        dp[0][0] = 0;
        FOR(i, 1, n) FOR(j, 1, min(k, i)) {
            ll maxDP = dp[j - 1][j - 1];
            FOR(x, j, i) {
                maximize(dp[i][j], maxDP + (sum[i] - sum[x - 1]));
                maximize(maxDP, dp[x][j - 1]);
            }
        }

        ll ans = 0;
        FOR(i, 1, n) FOR(j, 1, min(k, i)) maximize(ans, dp[i][j]);

        cout << ans << "\n";
    }
}

namespace sub6 {
    const int N = (int)2e3 + 3;
    ll dp[N][N][2];

    bool valid() {
        return n <= 2000;
    }

    void solve() {
        memset(dp, -0x3f, sizeof(dp));
        dp[0][0][0] = dp[0][0][1] = 0;
        ll ans = 0;
        FOR(i, 1, n) FOR(j, 1, min(i, k)) {
            dp[i][j][1] = max({1LL * a[i], dp[i - 1][j][1] + a[i], dp[i - 1][j - 1][0] + a[i]});
            dp[i][j][0] = max(dp[i - 1][j][0], dp[i][j][1]);
            maximize(ans, max({dp[i][j][0], dp[i][j][1]}));
            //cout << i << " " << j << "  " << dp[i][j][0] << " " << dp[i][j][1] << "\n";
        }
        cout << ans << "\n";
    }
}

void main_code() {
    cin >> n >> k;
    FOR(i, 1, n) cin >> a[i];

    if (sub3::valid()) sub3::solve();
    else if (sub1::valid()) sub1::solve();
    else if (sub2::valid()) sub2::solve();
    else if (sub5::valid()) sub5::solve();
    else if (sub6::valid()) sub6::solve();
}

int main() {
    ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    if (fopen(task".inp", "r")) {
        freopen(task".inp", "r", stdin);
        freopen(task".out", "w", stdout);
    }
    const bool MULTITEST = 0;
    int num_test = 1; if (MULTITEST) cin >> num_test;
    while (num_test--) { main_code(); cout << "\n"; }
}

/* Lak lu theo dieu nhac */

Compilation message (stderr)

feast.cpp: In function 'int main()':
feast.cpp:146:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  146 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
feast.cpp:147:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  147 |         freopen(task".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• 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: 0 / 29