Submission #898350

#	Time	Username	Problem	Language	Result	Execution time	Memory
898350		JakobZorz	Aliens (IOI16_aliens)	C++17	60 / 100	2123 ms	694760 KiB

aliens

#include"aliens.h"
#include<iostream>
#include<algorithm>
using namespace std;
typedef long long ll;
typedef pair<ll,ll>Line;

ll eval(Line l,ll x){
    return l.first*x+l.second;
}

struct CHT{
    int l,r;
    CHT*ch1,*ch2;
    Line cl;
    
    CHT(int l,int r):l(l),r(r),ch1(nullptr),ch2(nullptr){
        cl={0,1e18};
    }
    
    void add(Line line){
        int mid=(l+r)/2;
        if(eval(line,mid)<eval(cl,mid))
            swap(line,cl);
        
        if(l<r-1){
            if(eval(line,l)<eval(cl,l)){
                if(ch1==nullptr)
                    ch1=new CHT(l,mid);
                ch1->add(line);
            }
            
            if(eval(line,r)<eval(cl,r)){
                if(ch2==nullptr)
                    ch2=new CHT(mid,r);
                ch2->add(line);
            }
        }
    }
    
    ll get(ll x){
        int mid=(l+r)/2;
        ll res=eval(cl,x);
        //cout<<"res = "<<res<<"\n";
        //cout<<"line = "<<cl.first<<" "<<cl.second<<"\n";
        if(x>=mid&&ch2)
            res=min(res,ch2->get(x));
        if(x<mid&&ch1)
            res=min(res,ch1->get(x));
        //cout<<"res2 = "<<res<<"\n";
        return res;
    }
};

int n;
vector<ll>l,r;

ll sq(ll x){
    return x*x;
}

bool cmp(pair<int,int>a,pair<int,int>b){
    if(a.first==b.first)
        return a.second>b.second;
    return a.first<b.first;
}

ll take_photos(int N,int m,int k,vector<int>R,vector<int>C){
    n=N;
    vector<pair<int,int>>intervals_sorted;
    for(int i=0;i<n;i++){
        if(R[i]>C[i])
            swap(R[i],C[i]);
        intervals_sorted.emplace_back(R[i],C[i]);
    }
    sort(intervals_sorted.begin(),intervals_sorted.end(),cmp);
    int right_done=-1;
    for(auto i:intervals_sorted){
        if(i.second>right_done){
            l.push_back(i.first);
            r.push_back(i.second+1);
            right_done=i.second;
        }
    }
    n=(int)l.size();
    
    vector<vector<ll>>dp(n+1,vector<ll>(k+1));
    
    // cheapest way to cover first i segments with j squares
    for(int i=1;i<=n;i++){
        dp[i][0]=1e12;
    }
    
    for(int j=1;j<=k;j++){
        CHT cht(0,1<<20);
        for(int i=0;i<=n;i++){
            dp[i][j]=dp[i][j-1];
            //cout<<"get "<<cht.get(r[i-1])<<"\n";
            dp[i][j]=min(dp[i][j-1],cht.get(r[i-1])+r[i-1]*r[i-1]);
            if(i!=n){
                pair<ll,ll>el;
                el.first=-2*l[i];
                el.second=l[i]*l[i]+dp[i][j-1];
                if(i&&r[i-1]>l[i])
                    el.second-=sq(r[i-1]-l[i]);
                cht.add(el);
            }
        }
    }
    
    return dp[n][k];
}

• Subtask 1: 4 / 4
• Subtask 2: 12 / 12
• Subtask 3: 9 / 9
• Subtask 4: 16 / 16
• Subtask 5: 19 / 19
• Subtask 6: 0 / 40