제출 #1320992

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1320992		tolga	Feast (NOI19_feast)	C++20	0 / 100	84 ms	11964 KiB

feast

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define endl '\n'

int n, k;
vector<ll> a;
const ll INF = 1e18;

pair<ll, int> check(ll cost) {
  vector<array<pair<ll, int>, 2>> dp(n + 1);

  dp[1][0] = {0, 0};
  dp[1][1] = {a[0] - cost, 1};

  for (int i = 2; i <= n; i++) {
    dp[i][0] = max(dp[i - 1][0], dp[i - 1][1]);
    dp[i][1] =
        max(pair<ll, int>{dp[i - 1][0].first + a[i - 1] - cost,
                          dp[i - 1][0].second + 1},
            pair<ll, int>{dp[i - 1][1].first + a[i - 1], dp[i - 1][1].second});
  }

  return max(dp[n][0], dp[n][1]);
}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr), cout.tie(nullptr);

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

  ll left = 0, right = INF;
  while (left <= right) {
    ll mid = (left + right) / 2;
    int cnt = check(mid).second;
    if (cnt > k)
      left = mid + 1;
    else if (cnt < k)
      right = mid - 1;
    else {
      cout << check(left).first + left * k << endl;
      break;
    }
  }
}

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