HDU 1130 How Many Trees?

裸的卡特兰数

C++
#include<iostream>
#include<cstdio>
using namespace std;
#define base 10000
#define len 100
void multiply(int a[],int max,int b)
{
    int i,array=0;
    for(i=max-1;i>=0;i--)
    {
        array+=b*a[i];
        a[i]=array%base;
        array/=base;
    
    }
}

void divide(int a[],int max,int b)
{
    int i,div=0;
    for(i=0;i<max;i++)
    {
        div=div*base+a[i];
        a[i]=div/b;
        div%=b;
    }
}

int main()
{
    int n,i;
    int a[101][len];                                                                       
    memset(a[1],0,len*sizeof(int));
    for(i=2,a[1][len-1]=1;i<101;i++)
    {
        memcpy(a[i],a[i-1],len*sizeof(int));
        multiply(a[i],len,4*i-2);
        divide(a[i],len,i+1);
    }
    while(scanf("%d",&n)!=EOF)
    {
        for(i=0;i<len&&a[n][i]==0;i++);
        printf("%d",a[n][i++]);
        for(;i<len;i++)
        {
            printf("%04d",a[n][i]);
        }
        printf("\n");
    }
    return 0;
}

pascal
const
  modnum=10000;
type
  arraytype=array[0..100000] of longint;
var
  s:string;
  i,j,l,m,n,le:longint;
  h:arraytype;
procedure mul(var h:arraytype; k:longint);
var
  j:longint;
begin
  for j:=0 to le do h[j]:=h[j]*k;
  for j:=0 to le-1 do
  begin
    h[j+1]:=h[j+1]+h[j] div modnum;
    h[j]:=h[j] mod modnum;
  end;
  while h[le]>modnum do begin
    inc(le);
    h[le]:=h[le-1] div modnum;
    h[le-1]:=h[le-1] mod modnum;
  end;
end;
procedure devide(var h:arraytype; k:longint);
var
  d,o,r,i:longint;
begin
  r:=0;
  for i:=le downto 0 do
  begin
    d:=modnum*r+h[i];
    h[i]:=d div k;
    r:=d mod k;
  end;
end;
begin
  readln(n);
  h[0]:=1;
  for i:=1 to n do
  begin
    mul(h,i+n); devide(h,i);
  end;
  devide(h,n+1);
  while h[le]=0 do dec(le);
  write(h[le]);
  for i:=le-1 downto 0 do
  begin
    str(h[i],s);
    while length(s)<4 do s:='0'+s;
    write(s);
  end;
end.