x_1023的博客

#include<iostream>#include<cstring>#include<cstdio>#include<cstdlib>#include<algorithm>using namespace std;const int maxn=100005;int n,cnt,k;bool is[maxn];long long pre[maxn];long long prime[max

考察内容：Euler函数题意：求Σ(1分析：若gcd(i,j)=p,将i与j同除以p,则gcd(i/p,j/p)=1,而i,j最大值为n，则在p的情况下即为求i/p(i注意开long long不然会炸#include#include#include#include#includeusing namespace std;const