Co-prime HDU
阿新 • • 發佈:2018-12-12
Code:
#include<cstdio>
#include<cstring>
#include<cmath>
#include<iostream>
using namespace std;
const int maxn=100000+233;
typedef long long ll;
int v[maxn],vis[maxn];
int m[maxn];
int num; //質因子個數
ll ans=0;
ll A,B;
ll gcd(ll a,ll b){return b==0?a:gcd(b,a%b);}
void init (ll N){
int range=(int)sqrt(N),cnt=0;
for(int i=2;i<=range;++i){
if(!vis[i])v[++cnt]=i;
for(int j=1;j<=cnt&&v[j]*i<=range;++i){
vis[i*v[j]]=1;
if(i%v[j]==0)break;
}
}
ll t=N;
for(int i=1;i<=cnt;++i)if(N%v[i]==0) m[++num]=v[i];
for(int i=1;i<=num&&t!=1;++i)while(t%m[i]==0)t/=m[i];
if(t>range)m[++num]=t;
}
void dfs(int cur,ll lcm,int id)
{
if(cur>num)return;
lcm=m[cur]/gcd(m[cur],lcm)*lcm;
if(id)
ans+=(B/lcm)-((A-1)/lcm);
else ans-=(B/lcm)-((A-1)/lcm);
for( int i=cur+1;i<=num;++i)
dfs(i,lcm,!id);
}
int main()
{
int T;scanf("%d",&T);
for(int cas=1;cas<=T;++cas)
{
memset(v,0,sizeof(v));
memset(vis,0,sizeof(vis));
memset(m,0,sizeof(m));
num=ans=0;
ll N;
scanf("%lld%lld%lld",&A,&B,&N);
init(N);
for(int i=1;i<=num;++i)
dfs(i,m[i],1);
printf("Case #%d: %lld\n",cas,B-A-ans+1);
}
return 0;
}