加泰罗尼亚语用java代码编号 [英] Catalan number with java code

问题描述

这是我返回加泰罗尼亚语号码的代码，它给出了正确的答案，直到num = 6，而对于num> 6，答案返回错误，请我弄清楚原因。


我的尝试：

this is my code for returning a catalan number, it gives me the correct answer until the when num=6 and for num>6 the answers return are wrong, please i cant figure out why.

What I have tried:

return (isFactorial(2 * num)) /((isFactorial(num + 1)) * (isFactorial(num)));

推荐答案

你应该使用一个好的阶乘函数（ isFactorial 名称看似可疑）以便应用这样的公式。

请注意，在加泰罗尼亚语的维基百科页 [ ^ ]，您可以使用递归关系找到更好的公式来计算它们。试试，例如

You should use a good factorial function (isFactorial name looks suspicious) in order to apply such a formula.
Please note, on the very Wikipedia page of Catalan numbers[^], you may find better formulas, using recurrence relations, to compute them. Try, for instance

class Catalan
{
  static int catalan(int n)
  {
    int c = 1;
    for (int i = 0; i <n; ++i)
    {
      c = 2 * c * (2 *i + 1) / ( i + 2);
    }
    return c;
  }
  public static void main(String arg[])
  {
  for (int n=0; n<10; ++n)
    System.out.printf("catalan(%d) = %d\n", n, catalan(n));
  }
}

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