~~废话这样不MLE才怪~~
还是建议你去系统地学习一下欧拉函数
by Smile_Cindy @ 2019-11-12 16:40:54
@[云雨亦有情](/user/147987)
by Smile_Cindy @ 2019-11-12 16:40:58
@[云雨亦有情](/user/147987) ~~您也可以考虑一下反演~~
by CreeperLordVader @ 2019-11-12 16:47:32
@[CreeperLordVader](/user/68207) 请问反演是什么
by 云雨亦有情 @ 2019-11-12 16:57:57
@[云雨亦有情](/user/147987) 莫比乌斯反演
by CreeperLordVader @ 2019-11-12 17:23:52
```
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<iostream>
#include<cmath>
#include<algorithm>
using namespace std;
int main()
{
int a,b,c,d,e,f,g,h,i,j,k,l,m,n;
cin>>a;
for(b=1,d=0;a>=b;++b)
{
for(c=1;a>=c;++c)
{
if(__gcd(b-1,c-1)==1)
{
d++;
}
}
}
printf("%d",d);
}
by xb谢神noreply @ 2019-12-22 10:57:46