记录编号	146160	评测结果	AAAAAAAAAAAAAAAAAAAA
题目名称	[HNOI 2008]明明的烦恼	最终得分	100
用户昵称	HouJikan	是否通过	通过
代码语言	C++	运行时间	0.060 s
提交时间	2015-01-12 21:37:07	内存使用	0.43 MiB

#include <iostream>
#include <cstring>
#include <string>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <algorithm>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <list>
#include <vector>
#include <ctime>
#include <functional>
#define pritnf printf
#define scafn scanf
#define For(i,j,k) for(int i=(j);i<=(k);(i)++)
#define Clear(a) memset(a,0,sizeof(a))
using namespace std;
typedef long long LL;
typedef unsigned int Uint; 
const int INF=0x3fffffff;
//==============struct declaration==============
struct bign{
  const static int BASE=10000;
  int num[5100],length;
  bign(int number=0){
    memset(num,0,sizeof(num));
    length=0;
    while (number!=0){
       num[++length]=number%BASE;
       number/=BASE;
    }
  }
  bign operator *(const bign &A) const{
     bign res=0;
     for(int i=1;i<=length;i++)
       for(int j=1;j<=A.length;j++)
         res.num[i+j-1]+=num[i]*A.num[j];
     for(int i=1;i<=length+A.length;i++){
        res.num[i+1]+=res.num[i]/BASE;
        res.num[i]%=BASE;
     }
     res.length=length+A.length;
     while (res.length>1&&res.num[res.length]==0) res.length--;
     return res;
  }
  bign operator *(const int &A) const{
    bign temp=A;
    return temp*(*this);
  }
  void print(){
    while (length>0&&num[length]==0)
      length--;
    printf("%d",num[length]);
    for(int i=length-1;i>=1;i--)
      printf("%04d",num[i]);
    printf("\n");
  }
};
//==============var declaration=================
const int MAXN=10100;
int deg[MAXN],n,upn=0,downn=0,Free=0;
int up[MAXN],down[MAXN];
//==============function declaration============
int gcd(int a,int b){return a%b==0?b:gcd(b,a%b);}
//==============main code=======================
int main()
{  
freopen("bzoj_1005.in","r",stdin);
freopen("bzoj_1005.out","w",stdout);
  scanf("%d",&n);
  if (n==1) {
   int d;cin>>d;
   if (d==0||d==-1)    
printf("1\n");
  else printf("0\n");
    return 0; 
   }
  for(int i=1;i<=n;i++){
    scanf("%d",deg+i);
    if (deg[i]==-1){
      Free++;
      continue;
    }
    else{
      upn+=deg[i]-1;
      if (upn>n-2||deg[i]==0){
        printf("0\n");
        return 0;
      }
      for(int j=2;j<deg[i];j++)
        down[++downn]=j;
    }
  }
  
  for(int i=1;i<=upn;i++)
    up[i]=n-2-i+1; 
  //预处理  分子分母
  for(int D=1;D<=downn;D++){
    for(int U=1;U<=upn&&down[D]!=1;U++){
       int G=gcd(down[D],up[U]);
       down[D]/=G;up[U]/=G;
    }
    if (down[D]!=1){
      printf("0\n");
      return 0;
    }//不能满足要求
  }
  //约分
    bign res=1;
    for(int i=1;i<=upn;i++)
       res=res*up[i];
    for(int i=upn+1;i<=n-2;i++)
      res=res*Free;
  //计算 
  res.print();
  return 0;
}
//================fuction code====================