Submission #681382

#	Time	Username	Problem	Language	Result	Execution time	Memory
681382		iosif_andrei_	XOR Sum (info1cup17_xorsum)	C++14	100 / 100	1051 ms	37636 KiB

xorsum

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

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()
{
    cin >> n;

    int maxi = 0;

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

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

    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;

        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++;

            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;
                l++;
            }

            while (l <= n)
                bit ^= (n - (l++) + 1) & 1;
        }

        int last = n;

        for (int i = 1; i <= n; i++)
        {
            if (a[i].val + a[n].val < downLim)
            {
                low[i] = 0;
                continue;
            }

            while (last > 1 && a[i].val + a[last - 1].val >= downLim)
                last--;

            if (last < i)
                low[i] = i;
            else
                low[i] = last;
        }

        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;

        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:29:15: warning: unused variable 'm' [-Wunused-variable]
   29 |     int l, r, m, poz1, poz2, poz;
      |               ^
xorsum.cpp:29:18: warning: unused variable 'poz1' [-Wunused-variable]
   29 |     int l, r, m, poz1, poz2, poz;
      |                  ^~~~
xorsum.cpp:29:24: warning: unused variable 'poz2' [-Wunused-variable]
   29 |     int l, r, m, poz1, poz2, poz;
      |                        ^~~~
xorsum.cpp:29:30: warning: unused variable 'poz' [-Wunused-variable]
   29 |     int l, r, m, poz1, poz2, poz;
      |                              ^~~
xorsum.cpp:30:39: warning: unused variable 'sz' [-Wunused-variable]
   30 |     int res = 0, downLim, upLim, aux, sz, i;
      |                                       ^~

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