Submission #709333

#	Time	Username	Problem	Language	Result	Execution time	Memory
709333		awu	Discharging (NOI20_discharging)	C++14	100 / 100	140 ms	22548 KiB

Discharging

#include <bits/extc++.h>
using namespace std;

#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2")

#define int long long
#define f first
#define s second
#define all(x) x.begin(), x.end()
#define debug(x) do{auto y = x; cout << #x << " = " << y << endl;}while(0)
// #define endl "\n"
#define unordered_map __gnu_pbds::gp_hash_table
using pii = pair<int, int>;

const int inf = 1ll << 60;
const int MOD = 1e9 + 7;

int n;
vector<int> t;

int eval(pii f, int x) {
  if(x >= f.f) return inf;
  return (n - x) * t[f.f - 1] + f.s;
}

struct lichao {
  int tl, tr;
  pii f;
  lichao *lc, *rc;
  void insert(pii f2) {
    int tm = (tl + tr) / 2;
    if(eval(f2, tm) < eval(f, tm)) swap(f, f2);
    if(tl + 1 == tr) return;
    if(eval(f2, tl) <= eval(f, tl)) {
      if(!lc) {
        lc = new lichao{tl, tm, f2};
      } else {
        lc->insert(f2);
      }
    } else if(eval(f2, tr - 1) <= eval(f, tr - 1)) {
      if(!rc) {
        rc = new lichao{tm, tr, f2};
      } else {
        rc->insert(f2);
      }
    }
  }
  int query(int x) {
    int tm = (tl + tr) / 2;
    int res = eval(f, x);
    if(x < tm && lc) return min(res, lc->query(x));
    if(x >= tm && rc) return min(res, rc->query(x));
    return res;
  }
};

signed main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cin >> n;
  t.resize(n);
  for(int i = 0; i < n; i++) {
    cin >> t[i];
  }
  for(int i = 1; i < n; i++) {
    t[i] = max(t[i], t[i - 1]);
  }
  vector<int> dp(n);
  lichao lct{0, n, {n, 0}};
  for(int i = n - 1; i >= 0; i--) {
    dp[i] = lct.query(i);
    lct.insert({i, dp[i]});
  }
  cout << dp[0] << endl;
}

• Subtask 1: 9 / 9
• Subtask 2: 13 / 13
• Subtask 3: 25 / 25
• Subtask 4: 11 / 11
• Subtask 5: 14 / 14
• Subtask 6: 28 / 28