Submission #681275

#	Time	Username	Problem	Language	Result	Execution time	Memory
681275		USER	XOR Sum (info1cup17_xorsum)	C++14	0 / 100	1462 ms	12052 KiB

xorsum

#include <bits/stdc++.h> 
using namespace std;

class Input {
private:
    char* t;
    int sp;
    const int sz = 10000;

    char read()
    {
        if (sp == sz)
        {
            fread(t, 1, sz, stdin);
            sp = 0;
            return t[sp++];
        }
        else
            return t[sp++];
    }
public:
    Input()
    {
        sp = sz;
        t = new char[sz]();
    }

    Input& operator >> (int& n)
    {
        char c = read();

        while (c == ' ' || c == '\n')
            c = read();

        n = 0;

        int sng = 1;

        if (c == '-')
            sng = -1, c = read();

        while (c != '\0' && isdigit(c))
            n = n * 10 + (c - '0'), c = read();

        n *= sng;

        return *this;
    }

    Input& operator >> (char& s)
    {
        char c = read();

        while (c != '\0' && c == '\n')
            c = read();

        s = c;

        return *this;
    }

    Input& operator >> (long long& n)
    {
        char c = read();

        while (c == ' ' || c == '\n')
            c = read();

        n = 0;

        int sng = 1;

        if (c == '-')
            sng = -1, c = read();

        while (c != '\0' && isdigit(c))
            n = n * 10 + (c - '0'), c = read();

        n *= sng;

        return *this;
    }

    void getline(string& s)
    {
        char c = read();
        s = "";

        while (c != '\0' && c != '\n')
            s += c, c = read();
    }

    Input& operator >> (string& s)
    {
        char c;
        c = read();
        s = "";

        while (c == '\n' || c == ' ')
            c = read();

        while (c != '\n' && c != '\0' && c != ' ')
            s += c, c = read();

        return *this;
    }

    Input& operator >> (char* s)
    {
        char c;
        c = read();
        int i = 0;

        while (c == '\n' || c == ' ')
            c = read();

        while (c != '\n' && c != '\0' && c != ' ')
            s[i++] = c, c = read();

        return *this;
    }
};
class Output {
private:
    char* t;
    int sp;
    const int sz = 10000;

    void write(char c)
    {
        if (sp == sz)
        {
            fwrite(t, 1, sz, stdout);
            sp = 0;
            t[sp++] = c;
        }
        else
            t[sp++] = c;
    }

public:
    Output()
    {
        sp = 0;
        t = new char[sz]();
    }

    ~Output()
    {
        fwrite(t, 1, sp, stdout);
    }

    Output& operator << (int n)
    {
        if (n < 0)
        {
            write('-');
            n *= -1;
        }
        if (n <= 9)
            write(char(n + '0'));
        else
        {
            (*this) << (n / 10);
            write(char(n % 10 + '0'));
        }

        return *this;
    }

    Output& operator << (char c)
    {
        write(c);

        return *this;
    }

    Output& operator << (const char* s)
    {
        int i = 0;

        while (s[i] != '\0')
            write(s[i++]);

        return *this;
    }

    Output& operator << (long long n)
    {
        if (n < 0)
        {
            write('-');
            n *= -1;
        }
        if (n < 10)
            write(char(n + '0'));
        else
        {
            (*this) << (n / 10);
            write(char(n % 10 + '0'));
        }

        return *this;
    }

    Output& operator << (string s)
    {
        for (auto i : s)
            write(i);

        return *this;
    }

    void precizion(double x, int nr)
    {
        int p = int(floor(x));

        *this << p;

        if (nr == 0)
            return;

        write('.');

        for (int i = 1; i <= nr; i++)
        {
            x -= floor(x);
            x *= 10;

            write(int(x) + '0');
        }
    }
};

Input fin;
Output fout;

// (((1 << k) <= nr && nr < (1 << (k + 1))) || (nr >= (1 << k) + (1 << (k + 1))))

int v[1000001], X[1000001], n, POW[32], a[1000001];
const int p2 = 4194304;
int f[p2 + 2];
int* vp, * xp, * fp;
bool bit;

int main()
{
    f[p2 + 1] = -1;
    int maxi = 0;

    for (int i = 0; i <= 30; i++)
        POW[i] = (1 << i);

    fin >> n;

    for (int i = 1; i <= n; i++)
        fin >> v[i], maxi = max(maxi, v[i]);

    int stop = ceil(log2(maxi)) + 1, l, r, m, poz1, poz2;
    int res = 0, downLim, upLim, aux, sz;

    /*for (int k = 0; k < 22; k++)
    {
        bit = false;
        vp = v;
        vp++;

        xp = X;
        xp++;

        fp = f;
        
        while (*fp != -1)
            *fp = 0, fp++;

        for (int i = 1; i <= n; i++)
        {
            if (*vp & 1)
                *xp += POW[k];
            *vp >>= 1;

            f[*xp]++;

            vp++;
            xp++;
        }

        sz = 0;

        fp = f;
        int ind = 0;

        while (*fp != -1)
        {
            while (*fp)
                a[++sz] = ind, (*fp)--;
            ind++;
            fp++;
        }

        continue;

        aux = (1 << k) + (1 << (k + 1));
        downLim = POW[k];
        upLim = POW[k + 1] - 1;

        for (int i = 1; i <= n; i++)
        {
            poz1 = -1;
            l = i, r = n;

            while (l <= r)
            {
                m = (l + r) >> 1;

                if (a[i] + a[m] >= aux)
                {
                    poz1 = m;
                    r = m - 1;
                }
                else
                    l = m + 1;
            }

            if (poz1 != -1)
                bit ^= (n - poz1 + 1) & 1;

            poz1 = -1;

            l = i, r = n;

            while (l <= r)
            {
                m = (l + r) >> 1;

                if (a[i] + a[m] >= downLim)
                {
                    poz1 = m;
                    r = m - 1;
                }
                else
                    l = m + 1;
            }

            if (poz1 == -1 || a[i] + a[poz1] > upLim)
                continue;

            l = i, r = n;

            while (l <= r)
            {
                m = (l + r) >> 1;

                if (a[i] + a[m] <= upLim)
                {
                    poz2 = m;
                    l = m + 1;
                }
                else
                    r = m - 1;
            }

            bit ^= (poz2 - poz1 + 1) & 1;
        }

        if (bit)
            res += POW[k];
    }*/

    for (int k = 0; k <= 29; k++)
    {
        bit = false;
        vp = v;
        vp++;

        xp = X;
        xp++;

        for (int i = 1; i <= n; i++)
        {
            if (*vp & 1)
                *xp += POW[k];
            *vp >>= 1;

            a[i] = *xp;

            vp++;
            xp++;
        }

        sort(a + 1, a + n + 1);

        continue;

        aux = (1 << k) + (1 << (k + 1));
        downLim = POW[k];
        upLim = POW[k + 1] - 1;

        for (int i = 1; i <= n; i++)
        {
            poz1 = -1;
            l = i, r = n;

            while (l <= r)
            {
                m = (l + r) >> 1;

                if (a[i] + a[m] >= aux)
                {
                    poz1 = m;
                    r = m - 1;
                }
                else
                    l = m + 1;
            }

            if (poz1 != -1)
                bit ^= (n - poz1 + 1) & 1;

            poz1 = -1;

            l = i, r = n;

            while (l <= r)
            {
                m = (l + r) >> 1;

                if (a[i] + a[m] >= downLim)
                {
                    poz1 = m;
                    r = m - 1;
                }
                else
                    l = m + 1;
            }

            if (poz1 == -1 || a[i] + a[poz1] > upLim)
                continue;

            l = i, r = n;

            while (l <= r)
            {
                m = (l + r) >> 1;

                if (a[i] + a[m] <= upLim)
                {
                    poz2 = m;
                    l = m + 1;
                }
                else
                    r = m - 1;
            }

            bit ^= (poz2 - poz1 + 1) & 1;
        }

        if (bit)
            res += POW[k];
    }

    fout << res;

    return 0;
}

Compilation message (stderr)

xorsum.cpp: In function 'int main()':
xorsum.cpp:259:9: warning: unused variable 'stop' [-Wunused-variable]
  259 |     int stop = ceil(log2(maxi)) + 1, l, r, m, poz1, poz2;
      |         ^~~~
xorsum.cpp:260:39: warning: unused variable 'sz' [-Wunused-variable]
  260 |     int res = 0, downLim, upLim, aux, sz;
      |                                       ^~
xorsum.cpp: In member function 'char Input::read()':
xorsum.cpp:14:18: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   14 |             fread(t, 1, sz, stdin);
      |             ~~~~~^~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 7
• Subtask 2: 0 / 11
• Subtask 3: 0 / 21
• Subtask 4: 0 / 38
• Subtask 5: 0 / 23