欧拉函数模板

<span style="font-family: Arial, Helvetica, sans-serif;">#include <cstdio></span>

#include <iostream>#include <string>#include <cmath>#include <algorithm>#include <cstring>#include <queue>#include <map>#include <stack>#define INF 0x3f3f3f3#define MAX_N  3000005using namespace std;long long euler[MAX_N];void Euler(){    for(int i = 1; i<MAX_N; i++)        euler[i] = i;    for(int i = 2; i<MAX_N; i++)    {        if(euler[i] == i)            for(int j = i; j<MAX_N; j+=i)                euler[j] = (euler[j]/i)*(i-1);    }}

这是另一种实现方法

void init()      {          int i,j;          for (i=1;i<N;i++) e[i]=i;          for (i=2;i<N;i++)              if (e[i]==i)              {                  e[i]=i-1;                  for (j=i*2;j<N;j+=i) e[j]=e[j]/i*(i-1);              }      }