异或和之和 参考代码

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

typedef long long LL;
const int maxn = 100000 + 100;
int n;
LL ans;
LL num[maxn], bitSum[maxn], cnt[2];

LL solve(int dig) {
    memset(cnt, 0, sizeof(cnt));
    for (int i = 1; i <= n; ++i) {
        bitSum[i] = bitSum[i - 1] + ((num[i] >> dig) & 1);
        ++cnt[bitSum[i] & 1];
    }
    LL ret = 0;
    for (int i = 1; i <= n; ++i) {
        ret += cnt[(bitSum[i - 1] & 1) ^ 1];
        --cnt[bitSum[i] & 1];
    }
    return ret;
}

int main() {
#ifdef ExRoc
    freopen("test.txt", "r", stdin);
#endif // ExRoc
    ios::sync_with_stdio(false);

    cin >> n;
    for (int i = 1; i <= n; ++i) {
        cin >> num[i];
    }
    for (int i = 0; i <= 20; ++i) {
        ans += solve(i) << i;
    }
    cout << ans << endl;

    return 0;
}