Submission #681375

#	Time	Username	Problem	Language	Result	Execution time	Memory
681375		iosif_andrei_	XOR Sum (info1cup17_xorsum)	C++14	100 / 100	1481 ms	37640 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;
ofstream out("number.out");
 
// (((1 << k) <= nr && nr < (1 << (k + 1))) || (nr >= (1 << k) + (1 << (k + 1))))
 
int v[1000001], X[1000001], n, POW[32], szX, szY, low[1000001], high[1000001];
int* vp, * xp;
bool bit;
 
struct poz {
    int val, i;
}a[1000002], x[1000001], y[1000001];
 
bitset <1000001> b;
 
int main()
{
    fin >> n;
 
    int maxi = 0;
 
    for (int i = 0; i <= 30; i++)
        POW[i] = (1 << i);
 
    for (int i = 1; i <= n; i++)
    {
        fin >> v[i];
        maxi = max(maxi, v[i]);
    }
    //cout << '\n';
 
    int l, r, m, poz1, poz2, poz;
    int res = 0, downLim, upLim, aux, sz, i;
 
    for (int i = 1; i <= n; i++)
        a[i].i = i, a[i].val = 0;
 
    for (int k = 0; k <= 29; k++)
    {
        bit = false;
        vp = v;
        vp++;
 
        xp = X;
        xp++;
 
        szX = szY = 0;
 
        for (i = 1; i <= n; i++)
        {
            if (*vp & 1)
                *xp += POW[k], b[i] = true;
            else
                b[i] = false;
 
            *vp >>= 1;
 
            vp++;
            xp++;
        }
 
        for (i = 1; i <= n; i++)
            if (b[a[i].i])
                a[i].val += POW[k], y[++szY] = a[i];
            else
                x[++szX] = a[i];
 
        for (i = 1; i <= szX; i++)
            a[i] = x[i];
 
        for (int i = 1; i <= szY; i++)
            a[szX + i] = y[i];
 
        aux = (1 << k) + (1 << (k + 1));
        downLim = POW[k];
        upLim = POW[k + 1] - 1;
 
        //cout << aux << ' ' << downLim << ' ' << upLim << '\n';
 
        //for (int i = 1; i <= n; i++)
        //    cout << a[i].val << ' ';
        //cout << '\n';
 
        // case 1 --- (nr >= (1 << k) + (1 << (k + 1)))
 
        l = 1, r = 1;
 
        while (r <= n && a[l].val + a[r].val < aux)
            r++;
 
        if (r == n + 1)
        {
            while (l <= n && a[l].val + a[n].val < aux)
                l++; /*cout << 0 << ' ';*/
 
            r = n;
        }
 
        if (l != n + 1 && r != n + 1)
        {
            while (l < r)
            {
                while (l < r && a[l].val + a[r - 1].val >= aux)
                    r--;
 
                bit ^= (n - r + 1) & 1;
                //cout << r << ' ';
                l++;
            }
 
            while (l <= n)
                bit ^= (n - (l++) + 1) & 1; /*cout << l - 1 << ' ';*/
        }
 
        //cout << '\n';
 
        // case 2 --- (1 << k) <= nr && nr < (1 << (k + 1))
 
        // calc. down limit for each "i"
 
        /*l = 1, r = 1;
 
        while (r <= n && a[l].val + a[r].val < downLim)
            r++;
 
        if (r == n + 1)
        {
            while (l <= n && a[l].val + a[n].val < downLim)
                low[l++] = 0;
 
            r = n;
        }
 
        if (l != n + 1 && r != n + 1)
        {
            while (l < r)
            {
                while (l < r && a[l].val + a[r - 1].val >= downLim)
                    r--;
 
                low[l] = r;
                l++;
            }
 
            while (l <= n)
                low[l] = l++;
        }*/
 
        for (int i = 1; i <= n; i++)
        {
            l = i, r = n;
            poz = 0;
 
            while (l <= r)
            {
                m = (l + r) >> 1;
 
                if (a[i].val + a[m].val >= downLim)
                {
                    poz = m;
                    r = m - 1;
                }
                else
                    l = m + 1;
            }
 
            low[i] = poz;
        }
 
        // calc. up limit for each "i"
 
        l = 1, r = n;
 
        while (l <= r && a[l].val + a[r].val > upLim)
            r--;
 
        while (l <= r)
        {
            high[l] = r;
            l++;
 
            while (l <= r && a[l].val + a[r].val > upLim)
                r--;
        }
 
        while (l <= n)
            high[l++] = 0;
 
        //use limits
 
 /*       for (i = 1; i <= n; i++)
            cout << low[i] << ' ';
        cout << '\n';
        for (i = 1; i <= n; i++)
            cout << high[i] << ' ';
        cout << '\n' << '\n';*/
 
        for (i = 1; i <= n; i++)
            if (low[i] && high[i] && low[i] <= high[i])
                bit ^= (high[i] - low[i] + 1) & 1;
 
        if (bit)
            res += POW[k];
    }
 
    cout << res;
 
    return 0;
}

Compilation message (stderr)

xorsum.cpp: In function 'int main()':
xorsum.cpp:267:18: warning: unused variable 'poz1' [-Wunused-variable]
  267 |     int l, r, m, poz1, poz2, poz;
      |                  ^~~~
xorsum.cpp:267:24: warning: unused variable 'poz2' [-Wunused-variable]
  267 |     int l, r, m, poz1, poz2, poz;
      |                        ^~~~
xorsum.cpp:268:39: warning: unused variable 'sz' [-Wunused-variable]
  268 |     int res = 0, downLim, upLim, aux, sz, i;
      |                                       ^~
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: 11 / 11
• Subtask 3: 21 / 21
• Subtask 4: 38 / 38
• Subtask 5: 23 / 23