Submission #1209965

#	Time	Username	Problem	Language	Result	Execution time	Memory
1209965		lmquan	Feast (NOI19_feast)	C++17	100 / 100	920 ms	22736 KiB

feast

#define taskname ""
#include <bits/stdc++.h>
using namespace std;
const long long kInf = 100000000000000000;

int main() {
  if (fopen(taskname".inp", "r")) {
    freopen(taskname".inp", "r", stdin);
    freopen(taskname".out", "w", stdout);
  }
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);

  int n, k;
  cin >> n >> k;
  vector<int> a(n + 1);
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
  }

  auto Solve = [&](long long lambda) -> pair<long long, int> {
    vector<vector<pair<long long, int>>> dp(n + 1, vector<pair<long long, int>>(2, {0, 0}));
    dp[1][0] = make_pair(0, 0);
    dp[1][1] = make_pair(a[1] - lambda, 1);
    for (int i = 2; i <= n; i++) {
      dp[i][0] = max(dp[i - 1][0], dp[i - 1][1]);
      dp[i][1] = max(make_pair(dp[i - 1][0].first + a[i] - lambda, dp[i - 1][0].second + 1), make_pair(dp[i - 1][1].first + a[i], dp[i - 1][1].second));
    }
    return max(dp[n][0], dp[n][1]);
  };

  long long low = 0, high = kInf;
  while (low < high) {
    long long mid = (low + high + 1) / 2;
    pair<long long, int> s = Solve(mid);
    if (s.second >= k) {
      low = mid;
    } else {
      high = mid - 1;
    }
  }

  cout << Solve(low).first + low * k;

  return 0;
}

Compilation message (stderr)

feast.cpp: In function 'int main()':
feast.cpp:8:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
    8 |     freopen(taskname".inp", "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
feast.cpp:9:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
    9 |     freopen(taskname".out", "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 4 / 4
• Subtask 2: 8 / 8
• Subtask 3: 18 / 18
• Subtask 4: 10 / 10
• Subtask 5: 11 / 11
• Subtask 6: 20 / 20
• Subtask 7: 29 / 29