Submission #916407

#	Time	Username	Problem	Language	Result	Execution time	Memory
916407		andrei_iorgulescu	XOR Sum (info1cup17_xorsum)	C++14	77 / 100	1610 ms	85980 KiB

xorsum

#include <bits/stdc++.h>

using namespace std;

const int bulan = 23;

int n,a[1000005],v[1000005],vmax;
int fp[(1 << (bulan + 1)) + 1000];
int branza_topita;
int order[1000005],neworder[1000005];

int f(int x)
{
    if (branza_topita <= bulan)
        return fp[x];
    int st = 0,pas = 1 << 19;
    while (pas != 0)
    {
        if (st + pas <= n and v[st + pas] < x)
            st += pas;
        pas >>= 1;
    }
    return st + 1;
}

void sorteaza()
{
    vector<int>apoi;
    int idx = 0;
    for (int i = 1; i <= n; i++)
    {
        if ((a[order[i]] & (1 << branza_topita)) == 0)
            neworder[++idx] = order[i];
        else
            apoi.push_back(order[i]);
    }
    for (auto it : apoi)
        neworder[++idx] = it;
    for (int i = 1; i <= n; i++)
        order[i] = neworder[i];
    for (int i = 1; i <= n; i++)
        v[i] = a[order[i]] & ((1 << (branza_topita + 1)) - 1);
}

void prec()
{
    if (branza_topita > bulan)
        return;
    v[n + 1] = (1 << (branza_topita + 1));
    v[0] = 0;
    fp[0] = 1;
    for (int i = 1; i <= n + 1; i++)
    {
        for (int j = v[i - 1] + 1; j <= v[i]; j++)
            fp[j] = i;
    }
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    cin >> n;
    for (int i = 1; i <= n; i++)
    {
        cin >> a[i];
        vmax = max(vmax,a[i]);
    }
    for (int i = 1; i <= n; i++)
        order[i] = i;
    int ans = 0;
    for (int b = 0; (1 << b) <= 2 * vmax; b++)
    {
        branza_topita = b;
        //for (int i = 1; i <= n; i++)
          //  v[i] = a[order[i]] & ((1 << (b + 1)) - 1);
        sorteaza();
        prec();
        int cate = 0;
        for (int i = 1; i <= n; i++)
        {
            if ((v[i] & (1 << b)) == 0)
            {
                ///v[j] >= 2^b - v[i] si v[j] < 2^(b+1) - v[i], in plus j <= i
                int l = f((1 << b) - v[i]),r = f((1 << (b + 1)) - v[i]) - 1;
                if (l <= i and (min(i,r) - l + 1) % 2 == 1)
                    cate ^= 1;
            }
            else
            {
                ///v[j] < 2^(b+1) - v[i] sau v[j] >= 3 * 2^b - v[i]
                int r1 = f((1 << (b + 1)) - v[i]) - 1,l2 = f(3 * (1 << b) - v[i]);
                if (r1 % 2 == 1)
                    cate ^= 1;
                if (l2 <= i and (i - l2 + 1) % 2 == 1)
                    cate ^= 1;
            }
        }
        if (cate == 1)
            ans += (1 << b);
        if (branza_topita <= bulan)
        {
            for (int i = 0; i <= (1 << (branza_topita + 1)); i++)
                fp[i] = 0;
        }
    }
    cout << ans;
    return 0;
}

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