Submission #492135

#	Time	Username	Problem	Language	Result	Execution time	Memory
492135		Lam_lai_cuoc_doi	Aliens (IOI16_aliens)	C++17	0 / 100	1 ms	844 KiB

aliens

#include <bits/stdc++.h>

using namespace std;
using ll = long long;
using ld = long double;
using ull = unsigned long long;

template <class T>
void read(T &x)
{
    x = 0;
    register int c;
    while ((c = getchar()) && (c > '9' || c < '0'))
        ;
    for (; c >= '0' && c <= '9'; c = getchar())
        x = x * 10 + c - '0';
}

constexpr bool typetest = 0;

constexpr int N = 1e5 + 5;
constexpr ll Inf = 1e17;
int m, n, k;
pair<int, int> a[N];
ll cnt[N], sum[N];

struct ConvexHullTrick
{
    vector<ll> A, B;
    vector<int> line;
    vector<ld> point;
    ConvexHullTrick()
    {
        point.emplace_back(-Inf);
    }

    ld ff(int x, int y)
    {
        return (ld)1.0 * (B[y] - B[x]) / (A[x] - A[y]);
    }

    void Add(int i)
    {
        while ((int)line.size() > 2 || ((int)line.size() == 1 && A[line.back()] == A[i]))
        {
            if (A[line.back()] = A[i])
            {
                if (B[line.back()] > B[i])
                {
                    line.pop_back();
                    if (!line.empty())
                        point.pop_back();
                }
                else
                    break;
            }
            else
            {
                if (ff(i, line[line.size() - 2]) >= ff(i, line.back()))
                {
                    line.pop_back();
                    if (!line.empty())
                        point.pop_back();
                }
                else
                    break;
            }
        }

        if (line.empty() || A[line.back()] != A[i])
        {
            if (!line.empty())
                point.emplace_back(ff(line.back(), i));
            line.emplace_back(i);
        }
    }

    ll More(int x)
    {
        return cnt[x - 1] * a[x].second + sum[x - 1];
    }

    ll Get(int x)
    {
        int j = lower_bound(point.begin(), point.end(), -a[x].second) - point.begin();
        return A[line[j - 1]] * (-a[x].second) + B[line[j - 1]] + More(x);
    }
} f[4002];

long long take_photos(int N, int M, int K, vector<int> r, vector<int> c)
{
    /* Convert */
    m = M;
    n = N;
    k = K;
    for (int i = 1; i <= n; ++i)
    {
        a[i] = make_pair(r[i - 1] + 1, c[i - 1] + 1);
        if (a[i].first > a[i].second)
            swap(a[i].first, a[i].second);
    }

    sort(a + 1, a + n + 1, [&](const pair<int, int> &x, const pair<int, int> &y)
         { return x.second < y.second || (x.second == y.second && x.first > y.first); });

    vector<int> s;

    for (int i = 1; i <= n; ++i)
    {
        while (!s.empty() && a[i].first <= a[s.back()].first)
            s.pop_back();
        s.emplace_back(i);
    }

    n = s.size();

    for (int i = 1; i <= n; ++i)
    {
        a[i] = a[s[i - 1]];
    }

    /* End Convert */

    long long temp(0);

    for (int i = 1, j = 1, now = 0; i <= m; ++i)
    {
        if (j <= n && a[j].first == i)
        {
            now = a[j].second;
            ++j;
        }

        if (now >= i)
            temp += 2 * (now - i + 1) - 1;
    }

    for (int i = 1; i <= n; ++i)
    {
        if (i == n)
        {
            cnt[i] = (a[i].second - a[i].first + 1) * 2;
            sum[i] = -cnt[i] * a[i].second;
        }
        else if (a[i].second < a[i + 1].first)
        {
            cnt[i] = (a[i].second - a[i].first + 1) * 2;
            sum[i] = -cnt[i] * a[i].second;

            sum[i] += -(a[i + 1].first - a[i].second - 1) * (a[i + 1].first + a[i].second) + (a[i + 1].first - a[i].second - 1);
            cnt[i] += 2 * (a[i + 1].first - a[i].second - 1);
        }
        else
        {
            cnt[i] = (a[i + 1].first - a[i].first) * 2;
            sum[i] = -cnt[i] * a[i].second;
        }

        cnt[i] += cnt[i - 1];
        sum[i] += sum[i - 1];
    }

    ll ans(Inf);

    for (int i = 0; i <= k && i <= n; ++i)
    {
        f[i].A.resize(n + 2, 0);
        f[i].B.resize(n + 2, 0);
    }

    f[0].A[0] = 0;
    f[0].B[0] = 0;
    f[0].Add(0);

    for (int i = 1; i <= n; ++i)
        for (int j = min(i, k); j; --j)
        {
            ll v = f[j - 1].Get(i);
            f[j].A[i] = cnt[i];
            f[j].B[i] = -sum[i] + v;
            f[j].Add(i);
            if (i == n)
                ans = min(ans, v);
        }

    return ans + temp;
}

void Read()
{
    int m, n, k;
    cin >> n >> m >> k;
    vector<int> x(n), y(n);
    for (int i = 0; i < n; ++i)
        cin >> x[i] >> y[i];

    cout << take_photos(n, m, k, x, y);
}

void Solve()
{
}

Compilation message (stderr)

aliens.cpp: In function 'void read(T&)':
aliens.cpp:12:18: warning: ISO C++17 does not allow 'register' storage class specifier [-Wregister]
   12 |     register int c;
      |                  ^
aliens.cpp: In member function 'void ConvexHullTrick::Add(int)':
aliens.cpp:46:32: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
   46 |             if (A[line.back()] = A[i])

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