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 long using 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; }