bzoj 2705

orz教主的解法实在太神了

直接贴题解

 1 #include<bits/stdc++.h>
 2 #define inc(i,l,r) for(int i=l;i<=r;i++)
 3 #define dec(i,l,r) for(int i=l;i>=r;i--)
 4 #define link(x) for(edge *j=h[x];j;j=j->next)
 5 #define mem(a) memset(a,0,sizeof(a))
 6 #define inf 1e9
 7 #define ll long long
 8 #define succ(x) (1<<x)
 9 using namespace std;
10 ll read(){
11     ll x=0,f=1;char ch=getchar();
12     while(!isdigit(ch)){if(ch=='-')f=-1;ch=getchar();}
13     while(isdigit(ch))x=x*10+ch-'0',ch=getchar();
14     return x*f;
15 }
16 ll n,ans,t,s;
17 int main(){
18 //    freopen("data.in","r",stdin);
19     n=read();ans=1;
20     inc(i,2,(int)sqrt(n))if(n%i==0){
21         if(n==1)break;
22         for(t=1,s=0;n%i==0;s++)n/=i,t*=i;
23         ans*=(s+1)*t-s*t/i;
24     }
25     if(n!=1)ans*=n+n-1;
26     printf("%lld",ans);
27     return 0;
28 }

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