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#include <bits/stdc++.h>
using namespace std;
/**
* 功能：欧拉函数 互质的概念理解：gcd(x,y)=1
* @param x
* @return
*/
int phi(int x) {
int res = x;
for (int i = 2; i <= x / i; i++)
if (x % i == 0) {
res = res / i * (i - 1);
while (x % i == 0) x /= i;
}
if (x > 1) res = res / x * (x - 1);
return res;
int main() {
for (int i = 1; i <= 10; i++)
cout << "i=" << i << " phi[" << i << "]=" << phi(i) << endl;
//以9为例，与9形成gcd(x,9)=1的x共有6个，分别是(1,2,4,5,7,8)
return 0;
