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=;
    for(i=max-;i>=;i--)
    {
        array+=b*a[i];
        a[i]=array%base;
        array/=base;

    }
}

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

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

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