Submission #413315

#	Time	Username	Problem	Language	Result	Execution time	Memory
413315		Tc14	The short shank; Redemption (BOI21_prison)	C++17	35 / 100	2075 ms	14932 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;

pll calcDP(ll lambda) {

    ve<pll> DP(n, {LLINF, -1});

    DP[n - 1] = {0, 0};
    for (int i = n - 2; i >= 0; i--) {

        int z = INF;
        int cnt = 0;
        for (int j = i + 1; j < n; j++) {

            if (T[j] <= t || z <= t) cnt++;
            z = min(z, T[j]);
            z++;

            pll v = {DP[j].first + cnt + lambda, DP[j].second + 1};
            DP[i] = min(DP[i], v);
        }
    }

    pll ans = {LLINF, -1};
    int z = INF;
    int cnt = 0;
    for (int i = 0; i < n; i++) {

        if (T[i] <= t || z <= t) cnt++;
        z = min(z, T[i]);
        z++;

        pll v = {DP[i].first + cnt, DP[i].second};
        ans = min(ans, v);
    }

    return ans;
}

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 = 2e6;
    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: 0 / 10
• Subtask 5: 0 / 25
• Subtask 6: 0 / 20