hdu 1023 卡特兰数经典

code:

#include <iostream>
using namespace std;
int a[105][105];
int b[105];
void catalan() //求卡特兰数
{
    int i, j, len, carry, temp;
    a[1][0] = b[1] = 1;
    len = 1;
    for(i = 2; i <= 100; i++)
    {
        for(j = 0; j < len; j++) //乘法
        a[i][j] = a[i-1][j]*(4*(i-1)+2);
        carry = 0;
        for(j = 0; j < len; j++) //处理相乘结果
        {
            temp = a[i][j] + carry;
            a[i][j] = temp % 10;
            carry = temp / 10;
        }
        while(carry) //进位处理
        {
            a[i][len++] = carry % 10;
            carry /= 10;
        }
        carry = 0;
        for(j = len-1; j >= 0; j--) //除法
        {
            temp = carry*10 + a[i][j];
            a[i][j] = temp/(i+1);
            carry = temp%(i+1);
        }
        while(!a[i][len-1]) //高位零处理
        len --;
        b[i] = len;
    }
}
int main(int argc, char *argv[])
{
	int n,i;
	catalan();
	int j;
 	while (cin >> n)
 	{  
       for(j = b[n] - 1; j >= 0; j--)
	   {
  	 	 printf("%d",a[n][j]);

       }
        printf("\n");

    }
	return 0;
}