It is possible to make a catalan number in C with tail

[sivaprasad222]

I have the job of verifying and if it is possible to calculate the catalan number by means of the tail recursion, I could do the calculation with the stack recursion using the definition, but I could not do it by means of the tail recursion

int catalan(int n){
    if(n==0){
        return 1;
    }
    else{
        return 2*(2*n-1)*Catalan(n-1)/(n+1);
    }
}

[Lia]

sivaprasad222
Catalan(n-1) на catalan(n-1) менять не пробовали?

[arseniiv]

Aside from the typo mentioned above, the code seems correct. What’s the issue, exactly?

[npetric]

I think the question is whether it is possible to make tail recursion optimization

-- 23.11.2018, 20:11 --

I believe it is possible, but you may need a structure for quotient numbers

[Lia]

Какая оптимизация, ТС "просто не может скомпилировать".

[Sender]

Something like that, I think.

int catalan(int num,int den,int n)
{
     if (n==0)
         return num/den;
     return catalan(2*(2*n-1)*num,den*(n+1),n-1);
}

Should be called initially as "catalan(1,1,n)".
Perhaps, num and den can be divided by their GCD at each iteration, I guess.

[Lia]

Да, это в точности то, что уже предлагали по ссылке выше.

[Sender]

Оппаньки.

[Lia]

Вот и мне интересно, чего товарищ ищет ))