JWoC_Algorithms/XOR_sequence.cpp at master · JGEC-Winter-of-Code/JWoC_Algorithms · GitHub

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#include <bits/stdc++.h>
using namespace std;
int msb(int x)
{
    int ret = 0;
    while ((x >> (ret + 1)) != 0)
        ret++;
    return ret;
}
int xorRange(int l, int r)
{
    int max_bit = msb(r);
    int mul = 2;
    int ans = 0;
    for (int i = 1; i <= max_bit; i++) {

        if ((l / mul) * mul == (r / mul) * mul) {
            if (((l & (1 << i)) != 0) && (r - l + 1) % 2 == 1)
                ans += mul;
            mul *= 2;
            continue;
        }
        bool odd_c = 0;

        if (((l & (1 << i)) != 0) && l % 2 == 1)
            odd_c = (odd_c ^ 1);
        if (((r & (1 << i)) != 0) && r % 2 == 0)
            odd_c = (odd_c ^ 1);
        if (odd_c)
            ans += mul;
        mul *= 2;
    }
    int zero_bit_cnt = zero_bit_cnt = (r - l + 1) / 2;

    if (l % 2 == 1 && r % 2 == 1)
        zero_bit_cnt++;

    if (zero_bit_cnt % 2 == 1)
        ans++;

    return ans;
}
int main()
{
    int l,r;
    cin>>l>>r;
    cout << xorRange(l, r);

    return 0;
}