Submission #731604

#	Time	Username	Problem	Language	Result	Execution time	Memory
731604		jasen_penchev	Aliens (IOI16_aliens)	C++14	0 / 100	1 ms	296 KiB

aliens

/// Convex Hull Trick Optimization
#include <algorithm>
#include <iostream>
#include <utility>
#include <vector>
#include <deque>
#define endl '\n'
using namespace std;

const long long INF = (long long)(1e18);

struct line
{
    long long a, b;
    long long calc(long long x)
    {
        return (a * x + b);
    }
    long double intersect(line l)
    {
        return (long double)(l.b - b) / (a - l.a);
    }
};

long long take_photos(int n, int m, int k, vector<int> row, vector<int> col)
{
    vector< pair<int, int> > temp;
    for (int i = 0; i < n; ++ i)
    {
        temp.push_back({max(row[i], col[i]), min(row[i], col[i])});
    }
    sort(temp.begin(), temp.end());

    vector< pair<int, int> > interv;
    interv.push_back({-1, -1});
    for (auto [r, l] : temp)
    {
        while (interv.size() and interv.back().first >= l) interv.pop_back();
        interv.push_back({l, r});
    }
    n = interv.size() - 1;

    vector< vector<long long> > dp(n + 1, vector<long long>(2, INF));
    for (int i = 1; i <= n; ++ i)
    {
        dp[i][0] = 1ll * (interv[i].second - interv[1].first + 1) * (interv[i].second - interv[1].first + 1);
    }

    long long ret = dp[n][1];
    int pos = 0;
    for (int j = 2; j <= min(n, k); ++ j)
    {
        pos ^= 1;
        deque<line> dq;
        dq.push_back({-2ll * interv[j].first, dp[j - 1][pos ^ 1] + 1ll * interv[j].first * interv[j].first - 1ll * max(0, interv[j - 1].second - interv[j].first + 1) * max(0, interv[j - 1].second - interv[j].first + 1)});
        for (int i = j; i <= n; ++ i)
        {
            while (dq.size() >= 2 and dq[0].calc(interv[i].second + 1) >= dq[1].calc(interv[i].second + 1)) dq.pop_front();
            dp[i][pos] = dq[0].calc(interv[i].second + 1) + 1ll * (interv[i].second + 1) * (interv[i].second + 1);
            line curr = {-2ll * interv[i + 1].first, dp[i][pos ^ 1] + 1ll * interv[i + 1].first * interv[i + 1].first - 1ll * max(0, interv[i].second - interv[i + 1].first + 1) * max(0, interv[i].second - interv[i + 1].first + 1)};
            while (dq.size() >= 2 and curr.intersect(dq.back()) <= dq.back().intersect(dq[dq.size() - 2])) dq.pop_back();
            dq.push_back(curr);
        }
        ret = min(ret, dp[n][pos]);
    }

    return ret;
}

/**int main()
{
    ios :: sync_with_stdio(false);
    cin.tie(NULL); cout.tie(NULL);

    int n, m, k;
    cin >> n >> m >> k;

    vector<int> row, col;
    for (int i = 1; i <= n; ++ i)
    {
        int r, c;
        cin >> r >> c;
        row.push_back(r);
        col.push_back(c);
    }

    cout << take_photos(n, m, k, row, col) << endl;

    return 0;
}*/

Compilation message (stderr)

aliens.cpp: In function 'long long int take_photos(int, int, int, std::vector<int>, std::vector<int>)':
aliens.cpp:36:15: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   36 |     for (auto [r, l] : temp)
      |               ^

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