bzoj 3907 网格 bzoj2822 [AHOI2012]树屋阶梯——卡特兰数（阶乘高精度模板）

题目：https://www.lydsy.com/JudgeOnline/problem.php?id=3907

　　　https://www.lydsy.com/JudgeOnline/problem.php?id=2822

学到了阶乘高精度的板子。用起来好爽……

https://www.cnblogs.com/Tunix/p/4354348.html

#include<iostream>
#include<cstdio>
#include<cstring>
#define ll long long
using namespace std;
const ll mod=1e8;const int N=1e5+;
int n,m,x[N],v[N],p[N],tot;
ll a[N],b[N];
ll pw(ll x,int k)
{
  ll ret=;while(k){if(k&)ret*=x;x*=x;k>>=;}return ret;
}
void mul(ll a[],ll b)// a[] is already an iterator
{
  ll &l=a[],x=;
  for(int i=;i<=l;i++)
    {
      a[i]=a[i]*b+x;
      x=a[i]/mod;a[i]%=mod;
    }
  while(x)a[++l]=x%mod,x/=mod;
}
void getc(ll a[],int n,int m)
{
  memset(x,,sizeof x);
  for(int i=;i<=n;i++)x[i]++;
  for(int i=;i<=m;i++)x[i]--;
  for(int i=;i<=n-m;i++)x[i]--;
  for(int i=n;i>=;i--)
    if(!v[i])mul(a,pw(i,x[i]));
    else x[v[i]]+=x[i],x[i/v[i]]+=x[i];//+=x[i]!!!
}
void dec(ll a[],ll b[])
{
  ll &l=a[];
  for(int i=;i<=l;i++)
    {
      if(a[i]<b[i])a[i+]--,a[i]+=mod;
      a[i]-=b[i];
    }
  while(!a[l])l--;
}
void print(ll a[])
{
  int l=a[];
  printf("%lld",a[l]);
  for(int i=l-;i;i--)printf("%08lld",a[i]);
  printf("\n");
}
int main()
{
  scanf("%d%d",&n,&m);
  for(int i=;i<=n+m;i++)
    {
      if(!v[i])p[++tot]=i;
      for(int j=,k;j<=tot&&(k=p[j]*i)<=n+m;j++)
    {
      v[k]=p[j];if(i%p[j]==)break;
    }
    }
  a[]=a[]=b[]=b[]=;
  getc(a,n+m,m);
  getc(b,n+m,n+);
  dec(a,b);
  print(a);
  return ;
}

#include<iostream>
#include<cstdio>
#include<cstring>
#define ll long long
using namespace std;
const ll mod=1e8;const int N=1e5+;
int n,m,x[N],v[N],p[N],tot;
ll a[N],b[N];
ll pw(ll x,int k)
{
  ll ret=;while(k){if(k&)ret*=x;x*=x;k>>=;}return ret;
}
void mul(ll a[],ll b)// a[] is already an iterator
{
  ll &l=a[],x=;
  for(int i=;i<=l;i++)
    {
      a[i]=a[i]*b+x;
      x=a[i]/mod;a[i]%=mod;
    }
  while(x)a[++l]=x%mod,x/=mod;
}
void getc(ll a[],int n,int m)
{
  memset(x,,sizeof x);
  for(int i=;i<=n;i++)x[i]++;
  for(int i=;i<=m;i++)x[i]--;
  for(int i=;i<=n-m;i++)x[i]--;
  for(int i=n;i>=;i--)
    if(!v[i])mul(a,pw(i,x[i]));
    else x[v[i]]+=x[i],x[i/v[i]]+=x[i];//+=x[i]!!!
}
void dec(ll a[],ll b[])
{
  ll &l=a[];
  for(int i=;i<=l;i++)
    {
      if(a[i]<b[i])a[i+]--,a[i]+=mod;
      a[i]-=b[i];
    }
  while(!a[l])l--;
}
void print(ll a[])
{
  int l=a[];
  printf("%lld",a[l]);
  for(int i=l-;i;i--)printf("%08lld",a[i]);
  printf("\n");
}
int main()
{
  scanf("%d",&n);m=n;
  for(int i=;i<=n+m;i++)
    {
      if(!v[i])p[++tot]=i;
      for(int j=,k;j<=tot&&(k=p[j]*i)<=n+m;j++)
    {
      v[k]=p[j];if(i%p[j]==)break;
    }
    }
  a[]=a[]=b[]=b[]=;
  getc(a,n+m,m);
  getc(b,n+m,n+);
  dec(a,b);
  print(a);
  return ;
}

稍稍修改后的第二题代码