1057 N的阶乘（大数运算）

题目链接：51nod 1057 N的阶乘

#include<cstdio>
using namespace std;
typedef long long ll;
const int N = 10000;
const int mod = 1e8;
ll a[N] = {1};
int n;
int main(){
    int i, j, c, cnt;
    scanf("%d", &n);
    cnt = 1;
    for(j = 2; j <= n; ++j){
        for(c = i = 0; i <cnt; ++i){
            a[i] = a[i] * j + c;
            c = a[i] / mod;
            a[i] %= mod;
        }
        if(c > 0){
            a[i] = c;
            cnt++;
        }
    }
    printf("%lld", a[--cnt]);
    while(cnt){
        printf("%08lld", a[--cnt]);
    }
    return 0;
}