B3716 分解质因子 3

#include <bitset>
#include <vector>
#include <iostream>
#include <algorithm>

const int maxn = 100000008;

std::vector<int> prm, pre;  // pre is the min-factor array.
bool np[maxn];

void getPrime(const int N = 100000000) {//线性筛！
  pre.resize(N + 1);
  for (int i = 2; i <= N; ++i) {
    if (!np[i]) {
      prm.push_back(i); pre[i] = i;
    }
    for (auto p : prm) if (i * p <= N) {
      int k = i * p;
      np[k] = true;
      pre[k] = p;
      if (i % p == 0) break;
    } else break;
  }
}

int main() {
  std::ios::sync_with_stdio(false);
  std::cin.tie(nullptr);
  getPrime();
  int T, n;
  for (std::cin >> T; T; --T) {
    std::cin >> n;
    int ans = 0;
    while (n != 1) {
      ans ^= pre[n];
      n /= pre[n];
    }
    std::cout << ans << '\n';
  }
}

okk