light1341 唯一分解定理

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
#define ll long long
using namespace std;
int const MAX = 1e6 + 10;
int p[MAX];
bool u[MAX];
int num, cnt;
ll a, b, tmp;
 
void get_prime()  
{  
    memset(u, false, sizeof(u));
    for(int i = 2; i <= sqrt(MAX); i++)
        if(!u[i])
            for(int j = i * i; j <= MAX; j += i)
                u[j] = true;
    for(int i = 2; i <= MAX; i++)
        if(!u[i])
            p[cnt ++] = i;
}
 
void cal()
{
    for(int i = 0; i < cnt && p[i] <= sqrt(tmp); i++)
    {
        int cc = 0;
        while(tmp % p[i] == 0)
        {
            cc ++;
            tmp /= p[i];
        }
        num *= (cc + 1);
 
    }
    if(tmp > 1) //如果tmp不能被整分，说明还有一个素数是它的约数，此时cc=1
        num *= 2;
}
 
int main()
{
    int T;
    scanf("%d", &T);
    cnt = 0;
    get_prime();
    for(int ca = 1; ca <= T; ca++)
    {
        scanf("%lld %lld", &a, &b);
        if(a < b * b)
            printf("Case %d: 0\n", ca);
        else
        {
            num = 1;
            tmp = a;
            cal();
            num /= 2;
            for(int i = 1; i < b; i++)
                if(a % i == 0)
                    num --;
            printf("Case %d: %d\n", ca, num);
        }
    }
}