Submission #1029337

#	Time	Username	Problem	Language	Result	Execution time	Memory
1029337		MDario	The short shank; Redemption (BOI21_prison)	C++17	25 / 100	2088 ms	20048 KiB

prison

#include <bits/stdc++.h>
#include <functional>
#include <vector>
using namespace std;

#define F first
#define S second
typedef long long ll;

const string noyes[2] = {"NO", "YES"};
const ll INFLL = (1ll << 62);
const int INF = (1 << 30);
const int MAXN = 300'000;
const ll MOD = 1'000'000'007;

int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);

  ll n, D, T;
  cin >> n >> D >> T;

  ll a[n];
  for (int i = 0; i < n; i++)
    cin >> a[i];

  if (D == 1) {
    ll pref[n];
    {
      ll c = 0;
      ll last = INF;
      for (int i = 0; i < n; i++) {
        last = min(last + 1, a[i]);
        if (last <= T) {
          c++;
        }
        pref[i] = c;
        // cout << c << " ";
      }
      // cout << "\n";
    }

    ll suf[n];
    {
      stack<ll> slow;
      ll c = 0;
      ll last = INF;
      for (int i = n - 1; i >= 0; i--) {
        last = a[i];
        slow.push(i);
        while (!slow.empty() && abs(i - slow.top()) + last <= T) {
          c++;
          slow.pop();
        }
        suf[i] = c;
      }
      // for (int i = 0; i < n; i++)
      //   cout << suf[i] << " ";
      // cout << "\n";
    }

    ll ans = n;
    for (int i = 0; i + 1 < n; i++)
      ans = min(ans, pref[i] + suf[i + 1]);
    cout << ans << "\n";
    return 0;
  }
  int dp[n][2];
  {
    int c = 0;
    ll last = INF;
    for (int i = 0; i < n; i++) {
      last = min(last + 1, a[i]);
      c += (last <= T);
      dp[i][0] = c;
    }
  }
  for (int i = 0; i < D; i++) {
    int cur = i & 1;
    for (int t = i; t < n; t++)
      dp[t][cur ^ 1] = INF;
    for (int t = i; t < n; t++) {
      // cout << dp[t][cur] << " ";
      int c = 0;
      ll last = INF;
      for (int e = t + 1; e < n; e++) {
        last = min(last + 1, a[e]);
        c += (last <= T);
        dp[e][cur ^ 1] = min(dp[e][cur ^ 1], dp[t][cur] + c);
      }
    }
    // cout << "\n";
  }

  cout << dp[n - 1][D & 1] << "\n";
  return 0;
}

• Subtask 1: 15 / 15
• Subtask 2: 10 / 10
• Subtask 3: 0 / 20
• Subtask 4: 0 / 10
• Subtask 5: 0 / 25
• Subtask 6: 0 / 20