POJ 3421 X-factor Chains

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<time.h>
#include<iostream>
#include<algorithm>
#include<cmath>
using namespace std;

typedef long long LL;
int tol;
LL factor[100];
const int N = 2000001;
LL prime[N] = {0},num_prime = 0;
int isNotPrime[N] = {1, 1};

void findfac(long long n)
{
    for(int i=0; i<num_prime; i++)
    {
        if(n%prime[i]!=0) continue;
        while(1)
        {
            if(n==1||n%prime[i]!=0) break;
            factor[tol++]=prime[i];
            n=n/prime[i];
        }
        if(n==1) break;
    }
}

int num[100],tot;
long long c[25][25];

void init()
{
    c[1][1]=1;
    for(int i=1; i<=20; i++) c[i][0]=1;
    for(int i=2; i<=20; i++)
    {
        for(int j=1; j<=20; j++)
        {
            c[i][j]=c[i-1][j-1]+c[i-1][j];
        }
    }

    for(long i = 2 ; i < N ; i ++)
    {
        if(! isNotPrime[i])
            prime[num_prime ++]=i;
        for(long j = 0 ; j < num_prime && i * prime[j] <  N ; j ++)
        {
            isNotPrime[i * prime[j]] = 1;
            if( !(i % prime[j] ) ) 
                break;
        }
    }
}

int main()
{
    init();
    long long n;

    while(~scanf("%lld",&n))
    {
        if(n==1) {
            printf("%d %lld\n",1,1);
            continue;
        }
        tol=0;
        findfac(n);
        sort(factor,factor+tol);

        tot=0,num[tot]=1;
        for(int i=1;i<tol;i++)
        {
            if(factor[i]==factor[i-1]) num[tot]++;
            else
            {
                tot++;
                num[tot]=1;
            }
        }
        tot++;
        int sum=tol;
        int ans1=tol;
        long long ans2=1;

        for(int i=0;i<tot;i++)
        {
            ans2=ans2*c[sum][num[i]];
            sum=sum-num[i];
        }
        printf("%d %lld\n",ans1,ans2);
    }

    return 0;
}