Submission #917731

#	Time	Username	Problem	Language	Result	Execution time	Memory
917731		tarche	Feast (NOI19_feast)	C++17	100 / 100	272 ms	12480 KiB

feast

// @tarche
// Feast
// OJUZ
// Singapore NOI 2019
// https://oj.uz/problem/view/NOI19_feast
// 2024-01-28
#include <bits/stdc++.h>
#define forn(i, n) for (tint i = 0; i < tint(n); i++)
#define forsn(i, s, n) for (tint i = s; i < tint(n); i++)
#define dforn(i, n) for (tint i = tint(n) - 1; i >= 0; i--)
#define dforsn(i, s, n) for (tint i = tint(n) - 1; i >= s; i--)
#define sz(x) tint(x.size())
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define DBG(x) cerr << #x << " = " << x << endl

using namespace std;

#ifndef SMALL_TINT
using tint = long long;
#else
using tint = int;
#endif
using vi = vector<tint>;
using pii = pair<tint, tint>;

inline void fastIO() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
}

inline string YN(bool x, string y = "YES", string n = "NO") { return (x ? y : n); }

template <typename T>
inline void chmax(T &lhs, T rhs) {
  lhs = max(lhs, rhs);
}

template <typename T>
inline void chmin(T &lhs, T rhs) {
  lhs = min(lhs, rhs);
}

template <typename T, typename U>
ostream &operator<<(ostream &os, const pair<T, U> &p) {
  os << "(" << p.first << ", " << p.second << ")";
  return os;
}

template <typename T>
ostream &operator<<(ostream &os, const vector<T> &v) {
  os << "[";
  forn(i, sz(v)) {
    if (i > 0) os << ", ";
    os << v[i];
  }
  os << "]";
  return os;
}

template <typename T, size_t N>
ostream &operator<<(ostream &os, const array<T, N> &v) {
  os << "[";
  forn(i, N) {
    if (i > 0) os << ", ";
    os << v[i];
  }
  os << "]";
  return os;
}

const tint INF = 1e18;
pii solve(const vi &nums, tint lambda) {
  tint n = sz(nums);
  vector<array<pii, 2>> dp(n + 1, array<pii, 2>({make_pair(-INF, 0), make_pair(-INF, 0)}));
  dp[0][0].first = 0;

  forn(i, n) {
    chmax(dp[i + 1][0], dp[i][0]);
    chmax(dp[i + 1][0], dp[i][1]);
    chmax(dp[i + 1][1], {dp[i][1].first + nums[i], dp[i][1].second});
    if (dp[i + 1][0].first > -INF) {
      chmax(dp[i + 1][1], {dp[i][0].first + nums[i] - lambda, dp[i][0].second - 1});
    }
  }

  pii ans = max(dp[n][0], dp[n][1]);
  ans.second = -ans.second;
  ans.first += lambda * ans.second;
  return ans;
}

int main() {
  fastIO();

  tint n, k;
  cin >> n >> k;
  vi nums(n);
  forn(i, n) cin >> nums[i];

  tint lo = 0, hi = n * *max_element(all(nums));
  while (hi - lo > 1) {
    tint lambda = (hi + lo) / 2;
    if (solve(nums, lambda).second <= k) {
      hi = lambda;
    } else {
      lo = lambda;
    }
  }

  cout << solve(nums, hi).first << '\n';
}

• 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