利用递归解决倒杨辉三角函数，但是数大了就出错了



```c++
#include<bits/stdc++.h>
using namespace std;
unsigned long long f(unsigned long long x)
{
    if (x < 2) return 1;
    else return f(x - 1) * x;
}
int main()
{
    int n;
    scanf_s("%d", &n);
    for (int i = n - 1; i >= 0; i--)  //行数
    {
        for (int j = 0; j <= i; j++)
        {
            printf("%llu", f(i) / (f(j) * f(i - j)));
            if (j != i) printf(" ");
        }
        printf("\n");
    }

}


当n取值为30时，

![img](https://img-mid.csdnimg.cn/release/static/image/mid/ask/808230504076146.png "#left")
就不行了

img