OJ-Problems-Source/HDOJ/4466_autoAC.cpp

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#include <iostream>
#include <cstring>
#include <algorithm>
#include <cstdio>
#define maxn 5000500
#define M 1000000007
#define ll long long
using namespace std;
ll f[maxn];
ll count(ll x)
{
ll tot=0;
for (int i=1; i<=x/3; i++)
{
int tep=x-i;
if (tep/2>=max(i,(tep-i)/2+1))
{
tot=(tot+tep/2-max(i,(tep-i)/2+1)+1);
if (tot>=M) tot-=M;
}
}
return tot;
}
ll get(ll x)
{
if (f[x]!=0) return f[x];
ll tot=0;
for (int i=3; i<=x/2; i++)
if (x%i==0)
{
tot=(tot+get(i));
if (tot>=M) tot-=M;
}
f[x]=count(x)-tot;
if (f[x]<0) f[x]+=M;
return f[x];
}
ll power(ll x,ll y)
{
ll tot=1;
while (y)
{
if (y&1) tot=(tot*x)%M;
x=(x*x)%M;
y>>=1;
}
return tot;
}
int main()
{
ll n,ans,tep,cas=0;
while (scanf("%I64d",&n)!=EOF)
{
ans=0;
for (int i=1; i*i<=n; i++)
{
if (n%i==0)
{
tep=get(i);
tep=(tep*power(2,n/i-1))%M;
ans+=tep;
if (ans>=M) ans-=M;
if (i*i!=n)
{
tep=get(n/i);
tep=(tep*power(2,i-1))%M;
ans+=tep;
if (ans>=M) ans-=M;
}
}
}
printf("Case %I64d: %I64d\n",++cas,ans);
}
return 0;
}