Submission #474556

#	Time	Username	Problem	Language	Result	Execution time	Memory
474556		PurpleCrayon	Feast (NOI19_feast)	C++17	100 / 100	899 ms	17440 KiB

feast

#include <bits/stdc++.h>
using namespace std;
 
#define sz(v) int(v.size())
#define ar array
typedef long long ll;
const int MAXN = 3e5+10, MOD = 1e9+7;

using ld = long double;
#define double ld

int n, k;
ll a[MAXN], ps[MAXN];
pair<double, ll> dp[MAXN];

pair<double, ll> v(double x) { // cnt, cost
    fill(dp, dp+n, make_pair(0., 0ll));
    pair<double, ll> prv{0., 0};
    for (int i = 0; i < n; i++) {
        if (i) dp[i] = dp[i-1];
        // {ps[i] - ps[j] + dp[j].first, dp[j].second + 1}
        dp[i] = max(dp[i], make_pair(prv.first + ps[i] - x, prv.second + 1));
        prv = max(prv, make_pair(-ps[i] + dp[i].first, dp[i].second));
    }
    return dp[n-1];
}
void solve() {
    cin >> n >> k;
    for (int i = 0; i < n; i++) cin >> a[i];
    for (int i = 0; i < n; i++) ps[i] = a[i] + (i ? ps[i-1] : 0);

    bool bad = 0;
    for (int i = 0; i < n; i++) if (a[i] < 0) bad = 1;
    if (!bad) {
        cout << ps[n-1] << '\n';
        return;
    }


    double lo = 0, hi = 1e18;
    for (int rep = 0; rep < 100; rep++) {
        double mid = (lo + hi) / 2;
        if (v(mid).second >= k) lo = mid;
        else hi = mid;
    }
    double opt = lo;
    auto [ans, cnt] = v(opt);
    ans += opt * cnt;
    cout << llround(ans) << '\n';
}
int main(){
    ios::sync_with_stdio(false); cin.tie(0);
    int T=1;
    //cin >> T;
    while (T--) solve();
}

• 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