Submission #48425

#	Time	Username	Problem	Language	Result	Execution time	Memory
48425		wzy	Building Bridges (CEOI17_building)	C++11	100 / 100	149 ms	9164 KiB

building

#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pb push_back
long long w[100005] , h[100005];
long long n;
long long dp[100005];
struct line{
    int x , y;
    line(int x , int y){
        this->x = x , this->y = y;
    }
};

bool operator <(line a , line b){
    if(a.x == b.x) return a.y > b.y;
    else return a.x > b.x;
}
template <class type> 
class CHT{
    public : 
    bool cmp(type a , type b , type c){
        return ((double)((double) (c.y) - (a.y)) * ((double) (a.x) - (b.x))   <= ((double) ((double) (a.x) - (c.x)) * ((double) (b.y) - (a.y)) ) )  ; 
    }
    int sizex(){
        return cht.size();
    }
    void addLINE(type a){
            while(cht.size() >= 2 && cmp(cht[cht.size() - 2] , cht[cht.size() - 1] , a)){
                cht.pop_back();
            }
        cht.push_back(a);
    }
    int eval(type b , int a){
        int w = (b.x) * a + (b.y);
        return w;
    }
    void mergev(vector<type> nhcht){
        vector<type> newcht;
        for(int i = 0 ; i < nhcht.size() + cht.size() ; i++) newcht.pb(line(0,0));
        std::merge(nhcht.begin() , nhcht.end() , cht.begin() , cht.end() , newcht.begin() );
        cht.clear();
        for(int i = 0 ; i < newcht.size() ; i++) addLINE(newcht[i]);
    }
    int querymin(int x){
        if(cht.size() == 0) return (int) 1e18;
        int l = 0 , r = cht.size() - 1;
        r--;
        int ansj = -1;
        while(l<=r){
            int mid = (l+r)/2;
            if(eval(cht[mid] , x) >= eval(cht[mid + 1] , x)){
                l = mid + 1;
                ansj = mid;
            }
            else r = mid - 1;
        }
        int bestvalue = eval(cht.front() , x);
        if(ansj != -1) bestvalue = min(bestvalue , eval(cht[ansj] , x));
        ansj ++;
        if(ansj < cht.size()) bestvalue = min(bestvalue , eval(cht[ansj] , x));

        return bestvalue;
    }
    vector<type> vectorT(){
        return cht;
    }
    void clearv(){
        cht.clear();
    }
    vector<type> cht;
}; 

CHT <line> chts[33];

void addline(line a){
    vector<line> v;
    v.push_back(a);
    chts[0].mergev(v);
    for(int i = 0 ; i < 32 ; i++){
        int z = (1LL<<i);
        if(chts[i].sizex() > z){
            chts[i+1].mergev(chts[i].vectorT());
            chts[i].clearv();
        }
    }
    return ;
}


long long query(int x){

    long long bestvalue = (long long) 1e18;
    for(int i = 0 ; i < 32 ; i++){
        bestvalue  = min(bestvalue , chts[i].querymin(x));
    }
    return bestvalue;
}


int32_t main(){
    scanf("%lld" , &n);
    dp[0] = 0;
    for(int i = 1 ; i <=n ;i ++){
        scanf("%lld" , &h[i]);
    }
    w[0] = 0;
    for(int i = 1 ; i <=n ;i ++){
        scanf("%lld" , &w[i]);
        w[i] += w[i-1];
    }
    dp[1] = 0;
    addline(line(-2*h[1] , h[1]*h[1]  - w[1] ));
    for(int i = 2 ; i <= n ;i ++){
        dp[i] = query(h[i]) + h[i]*h[i] + w[i-1];
        addline(line(-2*h[i] , h[i]*h[i] - w[i] + dp[i]));
    }
    printf("%lld\n" , dp[n]);
}

Compilation message (stderr)

building.cpp: In instantiation of 'void CHT<type>::mergev(std::vector<_Tp>) [with type = line]':
building.cpp:79:21:   required from here
building.cpp:40:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int i = 0 ; i < nhcht.size() + cht.size() ; i++) newcht.pb(line(0,0));
building.cpp:43:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int i = 0 ; i < newcht.size() ; i++) addLINE(newcht[i]);
building.cpp: In instantiation of 'long long int CHT<type>::querymin(long long int) [with type = line]':
building.cpp:95:56:   required from here
building.cpp:61:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         if(ansj < cht.size()) bestvalue = min(bestvalue , eval(cht[ansj] , x));
building.cpp: In function 'int32_t main()':
building.cpp:102:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%lld" , &n);
     ~~~~~^~~~~~~~~~~~~
building.cpp:105:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%lld" , &h[i]);
         ~~~~~^~~~~~~~~~~~~~~~
building.cpp:109:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%lld" , &w[i]);
         ~~~~~^~~~~~~~~~~~~~~~

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