Submission #848216

#	Time	Username	Problem	Language	Result	Execution time	Memory
848216		quanlt206	Feast (NOI19_feast)	C++14	100 / 100	662 ms	11856 KiB

feast

#include <bits/stdc++.h>
#define X first
#define Y second
#define all(x) begin(x), end(x)
#define FOR(i, a, b) for (int i = (a); i <= (b); i++)
#define FORD(i, b, a) for (int i = (b); i >= (a); i--)
#define REP(i, a, b) for (int i = (a); i < (b); i++)
#define SQR(x) (1LL * (x) * (x))
#define MASK(x) (1LL << (x))
#define mxx max_element
#define mnn min_element

using namespace std;

typedef long long ll;
typedef long double ld;
typedef double db;
typedef pair<int, int> pii;
typedef pair<int, pii> piii;
typedef pair<ll, ll> pll;
typedef pair<ll, pll> plll;
typedef pair<ll, int> pli;

template<class A, class B>
    bool maximize(A& x, B y) {
        if (x < y) return x = y, true; else return false;
    }

template<class A, class B>
    bool minimize(A& x, B y) {
        if (x > y) return x = y, true; else return false;
    }
/* END OF TEMPLATE */

const int N = 3e5 + 7;

long double dp[N];

int trace[N], n, k;

ll a[N];

pll dynamic_dp(long double cost) {
    dp[0] = 0;
    FOR(i, 1, n) dp[i] = -1e18;
    long double tmp_val = 0;
    int idx = 0;
    FOR(i, 1, n) {
        dp[i] = dp[i - 1];
        if (maximize(dp[i], tmp_val + a[i] - cost)) trace[i] = idx;
        if (maximize(tmp_val, dp[i - 1] - a[i])) idx = i;
    }
    ll cnt = 0, res = 0;
    int i = n;
    while (i > 0) {
        if (abs(dp[i] - dp[i - 1]) < 1e-9) {
            i--;
            continue;
        }
        cnt++;
        res+=a[i] - a[trace[i]];
        i = trace[i] - 1;
    }
    return {cnt, res};
}

int main() {
//    freopen("test.INP", "r", stdin);
//    freopen("test.OUT", "w", stdout);
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cin>>n>>k;
    FOR(i, 1, n) cin>>a[i], a[i]+=a[i - 1];
    long double l = -1e12, r = 1e12;
    ll res = 0;
    FOR(i, 1, 100) {
        long double mid = (l + r) / 2.0;
        pll tmp = dynamic_dp(mid);
//        exit(0);
        if (tmp.X <= k) {
            maximize(res, tmp.Y);
            r = mid;
        }
        else l = mid;
    }
    cout<<res;
    return 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