Submission #1264932

#	Time	Username	Problem	Language	Result	Execution time	Memory
1264932		escobrand	Building Bridges (CEOI17_building)	C++20	100 / 100	35 ms	10564 KiB

building

#include <bits/stdc++.h>

using namespace std;
#define all(v) v.begin(),v.end()
#define pb push_back
#define ll long long
#define ld long double
#define fi first
#define se second
#define mk make_pair
typedef pair<int,int> pii;

const int maxn = 1e5 + 10;
ll a[maxn],pre[maxn],dp[maxn];

//
struct Line 
{
  ll a,b;
  mutable ld p;
  Line():a(0),b(0),p(LLONG_MIN){}
  Line(ll A,ll B):a(A),b(B),p(LLONG_MIN){}
  
  ll cal(ll x) const {return a * x + b;}
  
  bool operator < (const ll & x) const { return p < x;}
  
  bool operator < (const Line &o) const 
  {
    if(a != o.a)return a > o.a;
    return b < o.b;
  }
};

struct CHT_General : multiset<Line,less<void>>
{
  ld xcut(iterator a,iterator b) const { return (ld)(b->b - a->b) / abs(a->a - b->a);}
  
  bool check(iterator a,iterator b)
  {
    if(b == end())
    {
      a->p = LLONG_MAX;
      return 1;
    }
    
    if(a->a == b->a)return 0;
    
    a->p = xcut(a,b);
    return a->p < b->p;
  }
  
  void add(Line A)
  {
    iterator a = insert(A);
    iterator b = next(a);
    while(!check(a,b)) b = erase(b);
    if(a != begin())
    {
      b = prev(a);
      if(!check(b,a)) check(b,erase(a));
    }
    else return;
    
    while(b != begin())
    {
      a = prev(b);
      if(a->p >= b->p)
      {
          check(a,erase(b));
          b = a;
      }
      else break;
    }
  }
  
  ll cal(ll x) { return lower_bound(x)->cal(x);}
};
//

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    
    // https://oj.uz/problem/view/CEOI17_building?locale=en
    
    int n;
    cin>>n;
    for(int i = 1;i<=n;i++)cin>>a[i];
    for(int i = 1;i<=n;i++)
    {
      cin>>pre[i];
      pre[i] += pre[i-1];
    }
    
    CHT_General container;
    
    for(int i = 1;i<=n;i++)
    {
      if(i == 1)
      {
        dp[i] = 0;
      }
      else
      {
        dp[i] = container.cal(a[i]) + a[i] * a[i] + pre[i-1];
      }
      container.add(Line( a[i] * -2, a[i] * a[i] +dp[i] - pre[i] ));
    }
    
    cout<<dp[n];
    
    return 0;
}

• Subtask 1: 30 / 30
• Subtask 2: 30 / 30
• Subtask 3: 40 / 40