TOJ 10007 The last non-zero digit of n!

题目链接 :TOJ10007

10007 - The last non-zero digit of n!

Time Limit: 5000MS
Memory Limit: 65535KB

 

Description
Given an integer n, please output the last non-zero digit ofn!

For example, 5!=120, the last non-zero digit is 2, for 9!=362880 it is 8.


Input
One positive integer n. (0<n<10¹⁰⁰⁰¹)


Output
The last non-zero digit of n!


Sample Input
1



Sample Output
1

 

 

经典题目

#include<cstdio>#include<cstring>#include<cmath>#include<cstdlib>#include<algorithm>#include<string>#include<vector>#include<map>using namespace std;int mod[20]={1,1,2,6,4,2,2,4,2,8,4,4,8,4,6,8,8,6,8,2};char num[10005];int a[10005];int main(){    int len,t,c,i;    while(scanf("%s",num)==1)    {        t=1;        len=strlen(num);        for(i=0;i<len;i++)            a[i]=num[len-i-1]-'0';        while(len)        {            len-=!a[len-1];            t=t*mod[a[1]%2*10+a[0]]%10;            for(c=0,i=len-1;i>-1;i--)            {                c=c*10+a[i];                a[i]=c/5;                c%=5;            }        }        printf("%d\n",t);    }    return 0;}