USACO Section 3.2 Factorials - 高精度模拟~

     应改有更科学的方法吧~~我就是纯高精度了~~稍微估计了一下~~只做到1000位~~每次加进来都吧后缀0去掉~~最终输出第一位就ok了~~

Program:

/*  ID: zzyzzy12  LANG: C++  TASK: fact4*/    #include<iostream>    #include<istream>#include<stdio.h>    #include<string.h>    #include<math.h>    #include<stack>#include<algorithm>    #include<queue> #define oo 2000000000#define ll long longusing namespace std;int a[1005],n;void mul(int k){      int i,m;      for (i=1;i<=1000;i++) a[i]*=k;      i=1;      for (i=1;i<1000;i++)      {            a[i+1]+=a[i]/10;            a[i]%=10;       }       a[1000]%=10;      for (m=1;m<1000;m++)        if (a[m]!=0) break;      m--;      if (m)      for (i=1;i<1000-m;i++)       {             a[i]=a[i+m];             a[i+m]=0;      }}int main(){      freopen("fact4.in","r",stdin);        freopen("fact4.out","w",stdout);        memset(a,0,sizeof(a));       a[1]=1;       scanf("%d",&n);       for (int i=1;i<=n;i++)         mul(i);      printf("%d\n",a[1]);       return 0;   }