[UVa] 10061 How many zero's and how many digits.cpp

#include <cstdio>
#include <cmath>
using namespace std;
int main()
{
    int N,B;
    while (scanf("%d%d",&N,&B) != EOF){
        double digit = 0;
        int factor[801] = {0};

        double log10_B = log10(B);

        // N!
        for (int i = 2; i <= N; i++){
            //計算位數
            digit += (log10(i) / log10_B);  // 換底公式log(B,i)

            //計算i的質因數
            for (int temp = i, j = 2; j <= B; j++){
                while (temp % j == 0){
                    factor[j]++;
                    temp /= j;
                }
            }
        }

        // 計算有幾個0
        int nOf0 = 0;
        while (1){
            int temp = B;
            // 將因數從2~B跑過 看能不能使temp==1
            for (int i = 2; i <= B; i++){
                while (factor[i] && temp % i == 0){
                    factor[i]--;
                    temp /= i;
                }
            }
            if (temp == 1) nOf0++;
            else break;
        }

        printf("%d %d\n",nOf0,(int)digit+1);
    }
    return 0;
}