[模板] 线筛欧拉函数

#include <iostream>
#include <cstdlib>
typedef long long LL;

int phi[(int)1e7], p[(int)1e7];
int t;

void Phi(int n) {
for (int i = 2; i <= n; i++) {
if(!phi[i]) phi[p[t++] = i] = i - 1;
for (int j = 0; j < t && (LL)i * p[j] <= n; j++) {
if(i % p[j] == 0) {phi[i * p[j]] = phi[i] * p[j]; break;}
phi[i * p[j]] = phi[i] * (p[j] - 1);
}
}
}

int main() {
int n;
std::cin >> n;
Phi(n);
for (int i = 1; i <= n; i++) std::cout << phi[i] << ' ';
system("pause");
return 0;
}