Submission #413797

#	Time	Username	Problem	Language	Result	Execution time	Memory
413797		Tc14	The short shank; Redemption (BOI21_prison)	C++17	100 / 100	1715 ms	90596 KiB

prison

//#pragma GCC optimize("O3")
#include <bits/stdc++.h>
using namespace std;
#define ve vector
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
const int INF = 1e9 + 10;
const ll LLINF = (ll)1e18 + 10;

int n, d, t;
ve<int> T;

struct value {
    int pos;
    int inc;
    pll min;
    pll seg;
};

pll calcDP(ll lambda) {

    stack<value> U;
    pll seg;

    U.push({-1, 0, {LLINF, -1}, {LLINF, -1}});

    if (T[n - 1] > t) {
        U.push({n - 1, 0, {0, 0}, {0, 0}});
        seg = {LLINF, 0};
    }
    else seg = {1, 0};

    for (int i = n - 2; i >= 0; i--) {

        pll m = min(seg, U.top().min);
        pll v = m;

        v.first += lambda;
        v.second++;
        seg = min(seg, v);

        if (T[i] > t) {
            U.push({i, 0, m, seg});
            seg = {LLINF, 0};
        }
        else {

            int diff = t - T[i];

            seg.first++;
            U.top().inc++;
            U.top().min.first++;
            U.top().seg.first++;

            while (U.size() > 1 && (U.top().pos - i) <= diff) {

                U.top().seg.first++;
                seg = min(seg, U.top().seg);
                int inc = U.top().inc + 1;

                U.pop();

                U.top().inc += inc;
                U.top().min.first += inc;
                U.top().seg.first += inc;
            }
        }
    }

    return min(seg, U.top().min);
}

int main() {

    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);

    cin >> n >> d >> t;
    T = ve<int>(n);

    for (int i = 0; i < n; i++) {
        cin >> T[i];
    }

    ll lo = 0;
    ll hi = 4e6;
    ll c, x;

    while (lo != hi) {

        ll mi = (lo + hi) / 2;

        x = calcDP(mi).second;

        if (x > d) lo = mi + 1;
        else hi = mi;
    }

    tie(c, x) = calcDP(lo);

    cout << c - d * lo << endl;

    return 0;
}

• Subtask 1: 15 / 15
• Subtask 2: 10 / 10
• Subtask 3: 20 / 20
• Subtask 4: 10 / 10
• Subtask 5: 25 / 25
• Subtask 6: 20 / 20