873.欧拉函数-AcWing题库874.筛法求欧拉函数-AcWing题库#include<bits/stdc++.h>usingnamespacestd;intget_erlers(intx){intres=x;for(inti=2;i<=x/i;i++){if(x%i==0){res=res/i*(i-1);while(x%i