Co-prime
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 4090 Accepted Submission(s): 1619
Problem DescriptionGiven a number N, you are asked to count the number of integers between A and B inclusive which are relatively prime to N.
Two integers are said to be co-prime or relatively prime if they have no common positive divisors other than 1 or, equivalently, if their greatest common divisor is 1. The number 1 is relatively prime to every integer. InputThe first line on input contains T (0 < T <= 100) the number of test cases, each of the next T lines contains three integers A, B, N where (1 <= A <= B <= 1015) and (1 <=N <= 109). OutputFor each test case, print the number of integers between A and B inclusive which are relatively prime to N. Follow the output format below. Sample Input21 10 23 15 5 Sample OutputCase #1: 5Case #2: 10 思路:求1~m中与n互素的数的个数。
#include <cstdio>
#include <vector>
using namespace std;
typedef long long LL;
LL sieve(LL m,LL n)
{
vector<LL> divisor;
for(LL i=;i*i<=n;i++)
{
if(n%i==)
{
divisor.push_back(i);
while(n%i==) n/=i;
}
}
if(n>) divisor.push_back(n);
LL ans=;
for(LL mark=;mark<(<<divisor.size());mark++)
{
LL odd=;
LL mul=;
for(LL i=;i<divisor.size();i++)
{
if(mark&(<<i))
{
mul*=divisor[i];
odd++;
}
}
LL cnt=m/mul;
if(odd&) ans+=cnt;
else ans-=cnt;
}
return m-ans;
}
LL a,b,n;
int main()
{
int T;
scanf("%d",&T);
for(int cas=;cas<=T;cas++)
{
scanf("%lld%lld%lld",&a,&b,&n);
LL res=sieve(b,n)-sieve(a-,n);
printf("Case #%d: ",cas);
printf("%lld\n",res);
}
return ;
}