HDU 1131 Count the Trees

卡特兰数再乘上n的阶乘

#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);

        multiply(a[i],len,i);

        divide(a[i],len,i+1);

    }

    while(scanf("%d",&n),n!=0)

    {

        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;

}