sb题写挂还有资格参加省选？
写挂10+次，莫名RE，简直崩溃
最后选择了抄hzwer的代码
这题是一个裸的欧拉函数
把原题中的式子拆一下就行了
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 | #include<cstdio>#include<cmath>#include<algorithm>using namespace std;long long n,ans=0;long long phiQ(long long x){ long long t=x; for(long long i=2;i*i<=n;i++) if(x%i==0) { t=t/i*(i-1); while(x%i==0)x/=i; } if(x>1)t=t/x*(x-1); return t;}int main(){freopen("2705.in","r",stdin);freopen("2705.out","w",stdout);scanf("%lld",&n);for(long long i=1;i*i<=n;i++){ if(n%i==0){ ans+=(long long)i*phiQ(n/i); if(i*i<n)ans+=(long long)(n/i)*phiQ(i); }}printf("%lld\n",ans);return 0;} |
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