Submission #680800

#	Time	Username	Problem	Language	Result	Execution time	Memory
680800		iosif_andrei_	XOR Sum (info1cup17_xorsum)	C++14	45 / 100	1696 ms	27596 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]();
    }

    inline 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, t[1000002];
int* vp, * xp, * p;
long long bit[30];
const int inf = 100000000;

inline void add(int poz)
{
    for (int i = poz; i <= n; i += (i & -i))
        t[i]++;
}

inline void remove(int poz)
{
    for (int i = poz; i <= n; i += (i & -i))
        t[i]++;
}

inline int get(int poz)
{
    int s = 0;

    for (int i = poz; i; i -= (i & -i))
        s += t[i];

    return s;
}

inline void reset()
{
    p = (t + 1);

    while (*p != -1)
        *p = 0, p++;
}

struct poz { 
    int val, i;

}a[1000001], z2[1000001];

void Sort(int l, int r)
{
    if (l == r)
        return;

    int m = (l + r) >> 1;

    Sort(l, m);
    Sort(m + 1, r);

    int i = l, j = m + 1, sz = 0;

    while (i <= m && j <= r)
        if (a[i].val < a[j].val)
            z2[sz++] = a[i++];
        else
            z2[sz++] = a[j++];

    while (i <= m)
        z2[sz++] = a[i++];

    while (j <= r)
        z2[sz++] = a[j++];

    for (i = l, j = 0; i <= r; i++, j++)
        a[i] = z2[j];
}

int main()
{
    fin >> n;
    t[n + 1] = -1;

    int maxi = 0;

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

    int stop = ceil(log2(maxi));

    int i, k, l, r, aux;

    for (k = 0; k <= stop; k++)
    {
        // init. pointer for v
        vp = v;
        vp++;

        // init pointer for x
        xp = x;
        xp++;

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

            a[i].val = *xp;
            a[i].i = i;

            vp++;
            xp++;
        }

        Sort(1, n);

        int j = n;

        aux = (1 << (k + 1)) - 1;

        while (j >= 1 && a[1].val > aux - a[j].val)
            j--;

        l = r = 1;
        add(a[1].i);

        for (;j >= 1; j--)
        {
            aux = (1 << k) - a[j].val;
            while (l < n && a[l].val < aux)
            {
                remove(a[l].i);
                l++;
            }

            if (a[l].val < aux)
                break;

            aux = (1 << (k + 1)) - a[j].val - 1;
            while (r < n && a[r + 1].val <= aux)
            {
                r++;
                add(a[r].i);
            }

            bit[k] += get(a[j].i);
        }

        reset(); // reset AIB

        aux = (1 << k) + (1 << (k + 1)) - a[n].val;

        l = n + 1;

        while (l > 1 && a[l - 1].val >= aux)
        {
            l--;
            add(a[l].i);
        }

        if (l == n + 1)
            continue;

        bit[k] += get(a[n].i);

        for (j = n - 1; j >= 1; j--)
        {
            aux = (1 << k) + (1 << (k + 1)) - a[j].val;
            
            while (l <= n && a[l].val < aux)
            {
                remove(a[l].i);
                l++;
            }

            if (l == n + 1)
                break;

            bit[k] += get(a[j].i);
        }

        reset();
    }

    int res = 0;

    for (int k = 0; k <= 29; k++)
        if (bit[k] & 1)
            res += (1 << k);

    fout << res;

    return 0;
}

Compilation message (stderr)

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