Submission #1112156

#	Time	Username	Problem	Language	Result	Execution time	Memory
1112156		Aviansh	Building Bridges (CEOI17_building)	C++17	30 / 100	3040 ms	37316 KiB

building

#include <bits/stdc++.h>

using namespace std;

long long inf = 2e18;

struct line{
    long long m;
    long long c;
    double val(double x){
        return m*x+c;
    }
};

struct liChaoTree{
    line *st;
    line def;
    int n;
    liChaoTree(int siz){
        def.m=0;
        def.c=LLONG_MAX;
        int x = (int)ceil(log2(siz));
        st=new line[(1<<(x+1))];
        fill(st,st+(1<<(x+1)),def);
        n=siz;
    }
    void addLine(line lin, long long l=0, long long r=1000005, int ind=0){
        long long mid = (l+r)/2;
        if(st[ind].val(l)<=lin.val(l)&&st[ind].val(r)<=lin.val(r)){
            return;
        }
        if(st[ind].val(mid)>lin.val(mid)){
            swap(lin,st[ind]);
            //cout << "set " << ind << " to " << st[ind].m << " " << st[ind].c << "\n";
        }
        if(l==r)
            return;
        addLine(lin,l,mid,2*ind+1);
        addLine(lin,mid+1,r,2*ind+2);
        //cout << "added smth" << "\n";
    }
    double query(long long x, long long l=0, long long r=1000005, int ind=0){
        if(l==r&&r==x){
            //cout << "got " << st[ind].val(x) << " from " << st[ind].m << " " << st[ind].c << "\n";
            return st[ind].val(x);
        }
        if(x<l||x>r){
            return def.val(x);
        }
        long long mid = (l+r)/2;
        return min({st[ind].val(x),query(x,l,mid,ind*2+1),query(x,mid+1,r,ind*2+2)});
    }
};

signed main(){
    //ios::sync_with_stdio(0);
    //cin.tie(0);
    long long n;
    cin >> n;
    long long arr[n];
    for(long long &i : arr){
        cin >> i;
    }
    long long w[n];
    for(long long &i : w){
        cin >> i;
    }
    long long dp[n];
    dp[0]=0;
    dp[1]=arr[0]*arr[0]+arr[1]*arr[1]-2*arr[0]*arr[1];
    long long pref[n];
    pref[0]=w[0];
    for(int i = 1;i<n;i++){
        pref[i]=pref[i-1]+w[i];
    }
    liChaoTree lct(1000005);
    line l1,l2;
    l1.m=-2*arr[0];
    l2.m=-2*arr[1];
    l1.c=dp[0]-pref[0]+arr[0]*arr[0];
    l2.c=dp[1]-pref[1]+arr[1]*arr[1];
    //cout << "adding: \n";
    lct.addLine(l1);
    lct.addLine(l2);
    for(long long i = 2;i<n;i++){
        dp[i]=inf;
        //cout << dp[i] << " " << lct.query(arr[i]) << "\n";
        dp[i]=lct.query(arr[i]);
        dp[i]+=pref[i-1]+arr[i]*arr[i];
        line t;
        t.m=-2*arr[i];
        t.c=dp[i]-pref[i]+arr[i]*arr[i];
        lct.addLine(t);
    }
    cout << dp[n-1];
    return 0;
}

• Subtask 1: 30 / 30
• Subtask 2: 0 / 30
• Subtask 3: 0 / 40