Submission #659370

#	Time	Username	Problem	Language	Result	Execution time	Memory
659370		600Mihnea	The short shank; Redemption (BOI21_prison)	C++17	0 / 100	3 ms	340 KiB

prison

#include <bits/stdc++.h>

using namespace std;

const int N = 2000000 + 7;
const int INF = (int) 1e9 + 7;
int n;
int d;
int t;
int trebel[N];
bool block[N];
int gain[N];
int ant[N];

int compute2() {
  int sol = 0, last_blocked;
  for (int i = 1; i <= n; i++) {
    if (ant[i] == 0) {
      continue;
    }
    /// ant[i], i
    sol++;
    for (int j = ant[i]; j < i; j++) {
      if (block[j]) {
        sol--;
        break;
      }
    }
  }
  return sol;
}

int compute() {
  int sl = compute2();
  int last = INF, sol = 0;
  for (int i = 1; i <= n; i++) {
    if (block[i - 1]) {
      last = trebel[i];
    } else {
      last = min(last + 1, trebel[i]);
    }
    sol += (last <= t);
  }
  assert(sol == sl);
  return sol;
}

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

  freopen ("input.txt", "r", stdin);

  cin >> n >> d >> t;
  for (int i = 1; i <= n; i++) {
    cin >> trebel[i];
  }

  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= i; j++) {
      if (trebel[j] + i - j <= t) {
        ant[i] = j;
      }
    }
  }

  for (int iqd = 1; iqd <= d; iqd++) {
    int init = compute();
    int mx = -1, jj = -1;
    for (int i = 1; i < n; i++) {
      if (!block[i]) {
        block[i] = 1;
        gain[i] = init - compute();
        assert(gain[i] >= 0);
        if (gain[i] >= mx) {
          mx = gain[i];
          jj = i;
        }
        block[i] = 0;
      }
    }
    assert(1 <= jj && jj < n);
    block[jj] = 1;
  }
  cout << compute() << "\n";

  return 0;
}

Compilation message (stderr)

prison.cpp: In function 'int compute2()':
prison.cpp:16:16: warning: unused variable 'last_blocked' [-Wunused-variable]
   16 |   int sol = 0, last_blocked;
      |                ^~~~~~~~~~~~
prison.cpp: In function 'int main()':
prison.cpp:51:11: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   51 |   freopen ("input.txt", "r", stdin);
      |   ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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