Submission #320662

#	Time	Username	Problem	Language	Result	Execution time	Memory
320662		Sparky_09	Discharging (NOI20_discharging)	C++17	100 / 100	155 ms	16484 KiB

Discharging

#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define pll pair<ll,ll>

ll slope(pll x, pll y){
  if(x.first<y.first){
    swap(x,y);
  }
  return(y.second-x.second)/(x.first-y.first);
}

int main(){
	ios_base::sync_with_stdio(false);
	//freopen("input.txt", "r", stdin);

	int n;
	cin >> n;
	vector<ll> v(n+5), dp(n+5);
	vector<pair<ll,ll>> q;
	for(int i = 1; i <= n; i++){
	  cin >> v[i];
	  v[i] = max(v[i], v[i-1]);
	}

	q.emplace_back(n,0);
	int idx=0;

	for(int i = 1; i <= n; i++){
	  dp[i] = (ll)1e9;
	  if(v[i]==v[i+1]) continue;
	  
	  while(idx+1 < (int)q.size() and slope(q[idx],q[idx+1]) < v[i]){
	    idx++;
	  }

	  dp[i] = q[idx].second + q[idx].first * v[i];

	  while(q.size() > 1 and slope(q[q.size()-2], q[q.size()-1]) >= slope(q[q.size()-1], make_pair((ll)n-i, (ll)dp[i]))){
	    q.pop_back();
	  }

	  q.emplace_back(n - i, dp[i]);
	}
	cout << dp[n] << '\n';
}

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