Submission #413417

#	Time	Username	Problem	Language	Result	Execution time	Memory
413417		Tc14	The short shank; Redemption (BOI21_prison)	C++17	70 / 100	2035 ms	28808 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 SegmentTree {

    int Cap;
    ve<pll> Seg;
    ve<ll> L;

    int left(int x) { return 2 * x; }
    int right(int x) { return 2 * x + 1; }
    int parent(int x) { return x / 2; }

    void build() {
        Cap = 1 << (int)ceil(log2(n));
        Seg = ve<pll>(2 * Cap, {LLINF, -1});
        L = ve<ll>(2 * Cap);
    }

    void update(int a, int b) {
        update(a, b, 0, Cap - 1, 1);
    }

    void update(int a, int b, int i, int j, int curr) {

        if (a <= i && j <= b) {
            Seg[curr].first++;
            L[curr]++;
            return;
        }
        if (b < i || j < a) return;

        int m = (i + j) / 2;

        update(a, b, i, m, left(curr));
        update(a, b, m + 1, j, right(curr));

        Seg[curr] = min(Seg[left(curr)], Seg[right(curr)]);
        Seg[curr].first += L[curr];
    }

    void set(int i, pll x) {

        Seg[Cap + i] = x;
        int curr = parent(Cap + i);

        while (curr != 0) {
            Seg[curr] = min(Seg[left(curr)], Seg[right(curr)]);
            curr = parent(curr);
        }
    }

    pll getMin() {
        return Seg[1];
    }

};

pll calcDP(ll lambda) {

    stack<int> U;
    SegmentTree S;

    S.build();
    S.set(n - 1, {0, 0});

    if (T[n - 1] > t) U.push(n - 1);
    else S.update(n - 1, n - 1);

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

        pll v = S.getMin();
        v.first += lambda;
        v.second++;
        S.set(i, v);

        if (T[i] > t) U.push(i);
        else {

            int diff = t - T[i];
            S.update(i, n - 1);

            while (U.size() > 0 && (U.top() - i) <= diff) {
                S.update(U.top(), n - 1);
                U.pop();
            }
        }
    }

    return S.getMin();
}

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: 0 / 10
• Subtask 3: 20 / 20
• Subtask 4: 10 / 10
• Subtask 5: 25 / 25
• Subtask 6: 0 / 20