oj.uz

Submission #119389

# Submission time Handle Problem Language Result Execution time Memory
119389 2019-06-21T07:10:17 Z zubec Building Bridges (CEOI17_building) C++14
100 / 100
 160 ms 12920 KB 
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;

const int N = 100100;

int n;

ll h[N], w[N], dp[N];

const ld Fictive = 5e18;

struct line{
    ld k, b;
    set<line>::iterator it;
    line (ld _k, ld _b){
        k = _k;
        b = _b;
    }
    ld eval(ld x){
        return k*x+b;
    }
};
set<line> lineSet;

const bool operator < (const line& fi, const line& se){
    if (se.k == Fictive){
        auto it = fi.it;
        return next(it) != lineSet.end() && next(it)->k*se.b+next(it)->b >= it->k*se.b+it->b;
    }
    return fi.k > se.k || (fi.k == se.k && fi.b > se.b);
}

inline ld intersect(line l1, line l2){
    return (l1.b-l2.b)/(l2.k-l1.k);
}

inline bool to_erase(line fi, line se, line th){
    ld x = intersect(fi, th);
    return se.eval(x) <= th.eval(x);
}


void add(line l){
    l.k *= -1;
    l.b *= -1;
    auto it = lineSet.insert(l).first;
    line* pntr = (line*)&*it;
    pntr->it = it;
    if (it != lineSet.begin() && prev(it)->k == it->k){
        lineSet.erase(it);
        return;
    }
    if (next(it) != lineSet.end() && it->k == next(it)->k){
        lineSet.erase(next(it));
    }
    if (it != lineSet.begin() && next(it) != lineSet.end() && to_erase(*prev(it), *it, *next(it))){
        lineSet.erase(it);
        return;
    }
    while(it != lineSet.begin() && prev(it) != lineSet.begin() && to_erase(*prev(prev(it)), *prev(it), *it)){
        lineSet.erase(prev(it));
    }
    while(next(it) != lineSet.end() && next(next(it)) != lineSet.end() && to_erase(*it, *next(it), *next(next(it)))){
        lineSet.erase(next(it));
    }
}

ld get(ld x){
    line gt = *lineSet.lower_bound(line(Fictive, x));
    return -gt.eval(x);
}

int main(){
    ios_base::sync_with_stdio(0);cin.tie(0);

    cin >> n;
    for (int i = 1; i <= n; i++){
        cin >> h[i];
    }
    for (int i = 1; i <= n; i++){
        ll p;
        cin >> p;
        w[i] = w[i-1] + p;
    }


    /*for (int i = 2; i <= n; i++){
        dp[i] = 1e18;
        for (int j = 1; j < i; j++){
            dp[i] = min(dp[i], dp[j] + w[i-1]-w[j] + (h[i]-h[j])*(h[i]-h[j]));
        }
        //cout << i << ' ' << dp[i] << endl;
    }*/
    //cout << endl;
    for (int i = 1; i <= n; i++){
        if (i != 1){
            dp[i] = get(h[i])+h[i]*h[i]+w[i-1];
        }
        //cout << i << ' ' << dp[i] << endl;
        add({-2*h[i], dp[i] - w[i] + h[i]*h[i]});
    }
    cout << dp[n];

}

Compilation message

building.cpp: In function 'int main()':
building.cpp:102:16: warning: narrowing conversion of '(-2 * h[i])' from 'll {aka long long int}' to 'ld {aka long double}' inside { } [-Wnarrowing]
         add({-2*h[i], dp[i] - w[i] + h[i]*h[i]});
              ~~^~~~~
building.cpp:102:36: warning: narrowing conversion of '((dp[i] - w[i]) + (h[i] * h[i]))' from 'll {aka long long int}' to 'ld {aka long double}' inside { } [-Wnarrowing]
         add({-2*h[i], dp[i] - w[i] + h[i]*h[i]});
                       ~~~~~~~~~~~~~^~~~~~~~~~~

Subtask #1
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 384 KB Output is correct
2 Correct 2 ms 384 KB Output is correct
3 Correct 2 ms 384 KB Output is correct
4 Correct 3 ms 432 KB Output is correct
5 Correct 2 ms 384 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 79 ms 3876 KB Output is correct
2 Correct 79 ms 3832 KB Output is correct
3 Correct 81 ms 3832 KB Output is correct
4 Correct 72 ms 3704 KB Output is correct
5 Correct 76 ms 5648 KB Output is correct

Subtask #3
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 384 KB Output is correct
2 Correct 2 ms 384 KB Output is correct
3 Correct 2 ms 384 KB Output is correct
4 Correct 3 ms 432 KB Output is correct
5 Correct 2 ms 384 KB Output is correct
6 Correct 79 ms 3876 KB Output is correct
7 Correct 79 ms 3832 KB Output is correct
8 Correct 81 ms 3832 KB Output is correct
9 Correct 72 ms 3704 KB Output is correct
10 Correct 76 ms 5648 KB Output is correct
11 Correct 70 ms 3960 KB Output is correct
12 Correct 80 ms 3832 KB Output is correct
13 Correct 50 ms 3804 KB Output is correct
14 Correct 81 ms 3988 KB Output is correct
15 Correct 160 ms 12920 KB Output is correct
16 Correct 78 ms 5496 KB Output is correct
17 Correct 28 ms 3832 KB Output is correct
18 Correct 31 ms 3832 KB Output is correct