欧拉筛线性处理莫比乌斯函数

Posted 2021-10-11 hesorchen

欧拉筛线性处理莫比乌斯函数

代码

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

const int N = 1e6 + 5;

int prime[N];
bool vis[N];
int mobius[N];

void init()
{
    int times = 0;
    for (int i = 2; i < N; i++)
    {
        if (!vis[i])
            prime[++prime[0]] = i, mobius[i] = -1;
        for (int j = 1; j <= prime[0] && prime[j] * i < N; j++)
        {
            vis[i * prime[j]] = 1;
            if (i % prime[j] == 0)
                break;
            mobius[i * prime[j]] = -mobius[i];
        }
    }
}

int main()
{
    init();
    return 0;
}