Submission #477397

#	Time	Username	Problem	Language	Result	Execution time	Memory
477397		Tien_Noob	Building Bridges (CEOI17_building)	C++17	30 / 100	118 ms	3684 KiB

building

//Make CSP great again
//You're as beautiful as the day I lost you
#include <bits/stdc++.h>
#define TASK "TESTCODE"
using namespace std;
const int N = 2e5;
long long dp[N + 1], h[N + 1], w[N + 1], s = 0;
int n;
long long A(int i)
{
    return -2 * h[i];
}
long long B(int j)
{
    return dp[j] + h[j] * h[j];
}
long long C(int i)
{
    return h[i] * h[i] - w[i];
}
struct CHT
{
    bool Empty = true;
    vector<long double> Point;
    vector<int> Line;
    void Clear()
    {
        Point.clear();
        Line.clear();
        Empty = true;
    }
    long double Intersect(int i, int j)
    {
        return (long double)(B(j) - B(i))/(A(i) - A(j));
    }
    bool ok(int i)
    {
        return Intersect(i, Line.back()) > Intersect(i, Line[Line.size() - 2]);
    }
    void Add(int i)
    {
        Empty = false;
        while (Line.size() > 1 || (Line.size() == 1 && A(i) == A(Line.back())))
        {
            if (A(i) == A(Line.back()))
            {
                if (B(i) < B(Line.back()))
                {
                    Line.pop_back();
                    Point.pop_back();
                }
                else
                {
                    return ;
                }
            }
            else if (!ok(i))
            {
                Line.pop_back();
                Point.pop_back();
            }
            else
            {
                break;
            }
        }
        if (Line.empty())
        {
            Point.push_back(-1e18);
        }
        else
        {
            Point.push_back(Intersect(i, Line.back()));
        }
        Line.push_back(i);
    }
    long long Get(int i)
    {
        int j = upper_bound(Point.begin(), Point.end(), (long double)(h[i])) - Point.begin() - 1;
        return A(Line[j]) * h[i] + B(Line[j]) + C(i);
    }
};
CHT f[17];
void read()
{
    cin >> n;
    for (int i = 1; i <= n; ++ i)
    {
        cin >> h[i];
    }
    for (int i = 1; i <= n; ++ i)
    {
        cin >> w[i];
        s += w[i];
    }
}
void Update(int i)
{
    int pos = 0;
    vector<int> tmp = {i};
    while (pos < 17 && !f[pos].Empty)
    {
        for (int j : f[pos].Line)
        {
            tmp.push_back(j);
        }
        f[pos].Clear();
        ++pos;
    }
    sort(tmp.begin(), tmp.end(), [](int x, int y)
         {
             return A(x) > A(y);
         });
    for (int j : tmp)
    {
        f[pos].Add(j);
    }
}
void solve()
{
    dp[1] = -w[1];
    for (int i = 2; i <= n; ++ i)
    {
        dp[i] = 1e9;
        Update(i - 1);
        for (int j = 0; j < 17; ++ j)
        {
            if (!f[j].Empty)
            {
                dp[i] = min(dp[i], f[j].Get(i));
            }
        }
    }
    cout << dp[n] + s;
}
int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    if (fopen(TASK".INP", "r"))
    {
        freopen(TASK".INP", "r", stdin);
        //freopen(TASK".OUT", "w", stdout);
    }
    int t = 1;
    bool typetest = false;
    if (typetest)
    {
        cin >> t;
    }
    for (int __ = 1; __ <= t; ++ __)
    {
        //cout << "Case " << __ << ": ";
        read();
        solve();
    }
}

Compilation message (stderr)

building.cpp: In function 'int main()':
building.cpp:142:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  142 |         freopen(TASK".INP", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

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