Submission #646366

#	Time	Username	Problem	Language	Result	Execution time	Memory
646366		pls33	Mobile (BOI12_mobile)	C++17	0 / 100	551 ms	9640 KiB

mobile

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;

#pragma region dalykai
using p32 = pair<int, int>;
using p32u = pair<uint32_t, uint32_t>;
using p64 = pair<int64_t, int64_t>;
using p64u = pair<uint64_t, uint64_t>;
using vi16 = vector<int16_t>;
using vi16u = vector<uint16_t>;
using vi32 = vector<int>;
using vi32u = vector<uint32_t>;
using vi64 = vector<int64_t>;
using vi64u = vector<uint64_t>;
using vp32 = vector<p32>;
using vp32u = vector<p32u>;
using vp64 = vector<p64>;
using vp64u = vector<p64u>;
using vvi32 = vector<vi32>;
using vvi32u = vector<vi32u>;
using vvi64 = vector<vi64>;
using vvi64u = vector<vi64u>;
using vvp32 = vector<vp32>;
using vvp32u = vector<vp32u>;
using vvp64 = vector<vp64>;
using vvp64u = vector<vp64u>;

using pf32 = pair<float, float>;
using pf64 = pair<double, double>;
using pf80 = pair<long double, long double>;
using vf32 = vector<float>;
using vf64 = vector<double>;
using vf80 = vector<long double>;
using vpf32 = vector<pf32>;
using vpf64 = vector<pf64>;
using vpf80 = vector<pf80>;
using vvf32 = vector<vf32>;
using vvf64 = vector<vf64>;
using vvf80 = vector<vf80>;
using vvpf32 = vector<vpf32>;
using vvpf64 = vector<vpf64>;
using vvpf80 = vector<vpf80>;

template <typename key, typename val>
using ord_map = tree<key, val, less<key>, rb_tree_tag,
                     tree_order_statistics_node_update>;

template <typename key>
using ord_set = tree<key, null_type, less<key>, rb_tree_tag,
                     tree_order_statistics_node_update>;

const int BUF_SZ = 1 << 15;
inline namespace fast_in
{
    char buf[BUF_SZ];
    int pos;
    int len;

    char next_char(FILE *f)
    {
        if (pos == len)
        {
            pos = 0;
            len = (int)fread(buf, 1, BUF_SZ, f);

            if (!len)
            {
                return EOF;
            }
        }

        return buf[pos++];
    }

    int read_int(FILE *f)
    {
        int x;
        char ch;
        int sgn = 1;

        while (!isdigit(ch = next_char(f)))
        {
            if (ch == '-')
            {
                sgn *= -1;
            }
        }

        x = ch - '0';
        while (isdigit(ch = next_char(f)))
        {
            x = x * 10 + (ch - '0');
        }

        return x * sgn;
    }
}

/**
 * @brief gale programos flush_out kviest!!
 */
inline namespace fast_out
{
    char buf[BUF_SZ];
    int pos;

    void flush_out(FILE *f)
    {
        fwrite(buf, 1, pos, f);
        pos = 0;
    }

    void write_char(char c, FILE *f)
    {
        if (pos == BUF_SZ)
        {
            flush_out(f);
        }

        buf[pos++] = c;
    }

    void write_int(int x, FILE *f)
    {
        static char num_buf[100];

        if (x < 0)
        {
            write_char('-', f);
            x *= -1;
        }

        int len = 0;
        for (; x >= 10; x /= 10)
        {
            num_buf[len++] = (char)('0' + (x % 10));
        }

        write_char((char)('0' + x), f);
        while (len)
        {
            write_char(num_buf[--len], f);
        }
        write_char('\n', f);
    }
}
#pragma endregion

using fl_t = long double;
const fl_t __eps = 1e-3;

// !!!!!!!!!!!!!!
#define __x real
// !!!!!!!!!!!!!!
#define __y imag
using point_t = complex<fl_t>;

fl_t dot(point_t a, point_t b)
{
    return (conj(a) * b).__x();
}

fl_t cross(point_t a, point_t b)
{
    return (conj(a) * b).__y();
}

struct cht_t
{
    deque<point_t> hull, normal;

    void add(fl_t k, fl_t b)
    {
        point_t point(k, b);

        while (!normal.empty() && dot(normal.back(), point - hull.back()) < 0)
        {
            hull.pop_back();
            normal.pop_back();
        }

        if (!hull.empty())
        {
            normal.push_back(point_t(0, 1) * (point - hull.back()));
        }

        hull.push_back(point);
    }

    fl_t get(fl_t x)
    {
        point_t query(x, 1);

        auto it = lower_bound(normal.begin(), normal.end(),
                              query,
                              [](point_t a, point_t b)
                              {
                                  return cross(a, b) > 0;
                              });

        return dot(query, hull[it - normal.begin()]);
    }
};

void add(point_t p, cht_t &cht)
{
    fl_t k = -2ll * p.__x();
    fl_t b = p.__x() * p.__x() + p.__y() * p.__y();

    // - nes reik minimumo mum
    cht.add(-k, -b);
}

fl_t query(fl_t x, cht_t &cht)
{
    return x * x - cht.get(x);
}

fl_t ternary_search(fl_t l, fl_t r, cht_t &cht)
{
    while (r - l > __eps)
    {
        fl_t m_l = l + (r - l) / 3;
        fl_t m_r = r - (r - l) / 3;

        if (query(m_l, cht) >= query(m_r, cht))
        {
            l = m_l;
        }
        else
        {
            r = m_r;
        }
    }

    return query(l, cht);
}

int main()
{
#ifndef _AAAAAAAAA
    ios_base::sync_with_stdio(false);
    cin.tie(0);
#else
    freopen("mobile.in", "r", stdin);
#ifndef __linux__
    atexit([]()
           {
        freopen("con", "r", stdin);
        system("pause"); });
#endif
#endif

    int n, length;
    cin >> n >> length;

    cht_t cht;
    for (size_t i = 0; i < n; i++)
    {
        fl_t a, b;
        cin >> a >> b;

        if (fabsl(a) < __eps)
        {
            // ????????
            a = __eps;
        }
        add({a, b}, cht);
    }

    cout << sqrt(ternary_search(0, length + __eps, cht)) << '\n';

    return 0;
}

Compilation message (stderr)

mobile.cpp:8: warning: ignoring '#pragma region dalykai' [-Wunknown-pragmas]
    8 | #pragma region dalykai
      | 
mobile.cpp:151: warning: ignoring '#pragma endregion ' [-Wunknown-pragmas]
  151 | #pragma endregion
      | 
mobile.cpp: In function 'int main()':
mobile.cpp:262:26: warning: comparison of integer expressions of different signedness: 'size_t' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
  262 |     for (size_t i = 0; i < n; i++)
      |                        ~~^~~

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