Submission #524071

#	Time	Username	Problem	Language	Result	Execution time	Memory
524071		DanerZein	Discharging (NOI20_discharging)	C++14	100 / 100	385 ms	17932 KiB

Discharging

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int MAX_N=1e6+10;
const ll MAX=1e9;
struct line{
  ll m,b;
  line(ll mm,ll bb){
    m=mm; b=bb;
  }
  ll eval(ll x){
    return m*x+b;
  }
  long double intersect(line l){
    return (long double)(b-l.b)/(l.m-m);
  }
  /* ll intersect(line l){
    ll le=1;
    ll ri=1;
    while(eval(ri)>l.eval(ri)){
      le=ri;
      ri*=2;
    }
    while(ri>le){
      ll mid=(le+ri)/2;
      if(eval(mid)<=l.eval(mid)) ri=mid;
      else le=mid+1;
    }
    return ri;
  }*/
};
ll val[MAX_N];
int main(){
  int n; cin>>n;
  for(int i=1;i<=n;i++){
    cin>>val[i];
    val[i]=max(val[i],val[i-1]);
  }
  deque<line> dq;
  dq.push_front({MAX,MAX});
  ll ans=0;
  for(int i=1;i<=n;i++){
    int t=dq.size();
    line nl={(n-i+1),ans};
    while(t>=2 && nl.intersect(dq[t-2])<=dq[t-1].intersect(dq[t-2])){
      dq.pop_back();
      t--;
    }
    dq.push_back(nl);
    while(dq.size()>=2 && dq[0].eval(val[i])>=dq[1].eval(val[i]))
      dq.pop_front();
    
    ans=dq.front().eval(val[i]);
  }
  cout<<ans<<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