Submission #1106206

#	Time	Username	Problem	Language	Result	Execution time	Memory
1106206		manhlinh1501	Feast (NOI19_feast)	C++17	100 / 100	138 ms	14560 KiB

feast

#include<bits/stdc++.h>
using namespace std;
using i64 = long long;

template<class X, class Y>
bool minimize(X &x, const Y &y) {
    if (x > y) {
        x = y;
        return true;
    }
    return false;
}
template<class X, class Y>
bool maximize(X &x, const Y &y) {
    if (x < y) {
        x = y;
        return true;
    }
    return false;
}
using pli = pair<i64, int>;
const int MAXN = 3e5 + 5;
const int oo32 = 1e9 + 5;
const i64 oo64 = 1e18 + 5;

int N, K;
i64 a[MAXN];

namespace subtask1 {
    bool is_subtask() {
        for(int i = 1; i <= N; i++) {
            if(a[i] < 0) return false;
        }
        return true;
    }
    void solution() {
        if(is_subtask() == false) return;
        i64 ans = accumulate(a + 1, a + N + 1, 0LL);
        cout << ans;
        exit(0);
    }
}

namespace subtask2 {
    bool is_subtask() {
        int c = 0;
        for(int i = 1; i <= N; i++)
            c += (a[i] < 0);
        return c <= 1;
    }

    void solution() {
        if(is_subtask() == false) return;
        i64 tot = accumulate(a + 1, a + N + 1, 0LL);
        i64 ans = tot;
        for(int i = 1; i <= N; i++) ans = max(ans, tot - a[i]);
        cout << ans;
        exit(0);
    }
}

namespace subtask3 {
    bool is_subtask() {
        return K == 1;
    }
    i64 dp[MAXN];

    void solution() {
        if(is_subtask() == false) return;
        for(int i = 1; i <= N; i++) dp[i] = max(dp[i - 1], 0LL) + a[i];
        cout << *max_element(dp + 1, dp + N + 1);
        exit(0);
    }
}

namespace subtask {
    void solution() {
        for(int i = 1; i <= N; i++) a[i] += a[i - 1];
        vector<vector<i64>> dp(N + 1, vector<i64>(K + 1, -oo64));
        vector<i64> maxx(N + 1, 0);
        dp[0][0] = 0;
        for(int i = 1; i <= N; i++) maxx[i] = max(maxx[i - 1], -a[i]);
        for(int j = 1; j <= K; j++) {
            for(int i = 1; i <= N; i++)
                maximize(dp[i][j], maxx[i - 1] + a[i]);
            for(int i = 1; i <= N; i++) maxx[i] = max(maxx[i - 1], dp[i][j]);
            for(int i = 1; i <= N; i++) maxx[i] = max(maxx[i - 1], maxx[i] - a[i]);
        }
        i64 ans = 0;
        for(int i = 1; i <= N; i++) {
            for(int j = 1; j <= K; j++)
                maximize(ans, dp[i][j]);
        }
        cout << ans;
    }
}

namespace solver {
    pli dp[MAXN][2];

    void calc(i64 mid) {
        for(int i = 0; i <= N; i++) dp[i][0] = dp[i][1] = pli(-oo64, -oo64);
        dp[0][0] = pli(0, 0);
        for(int i = 1; i <= N; i++) {
            dp[i][0] = max(dp[i - 1][0], dp[i - 1][1]);
            dp[i][1] = max(make_pair(dp[i - 1][0].first + a[i] - mid, dp[i - 1][0].second + 1),
                           make_pair(dp[i - 1][1].first + a[i], dp[i - 1][1].second));
        }
    }

    void solution() {
        i64 low = 0, high = oo64;
        i64 ans = 0;
        while(low <= high) {
            i64 mid = (low + high) / 2;
            calc(mid);
            if(max(dp[N][0], dp[N][1]).second >= K) {
                ans = mid;
                low = mid + 1;
            } else high = mid - 1;
        }
        calc(ans);
        cout << max(dp[N][0], dp[N][1]).first + K * ans;
    }
}

signed main() {
#define task "code"
    if(fopen(task".inp", "r")) {
        freopen(task".inp", "r", stdin);
        freopen(task".out", "w", stdout);
    }
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    cin >> N >> K;
    for(int i = 1; i <= N; i++) cin >> a[i];
    subtask1::solution();
    subtask3::solution();
    subtask2::solution();
    solver::solution();
    return (0 ^ 0);
}

Compilation message (stderr)

feast.cpp: In function 'int main()':
feast.cpp:130:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  130 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
feast.cpp:131:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  131 |         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: 29 / 29