nth_catalan

/**
 *    author:  Mathura Tudu
 *    created: 25.04.2020 20:52:53 IST
**/

#include <bits/stdc++.h>

using namespace std;

using ull = unsigned long long int;

ull binomial(int n, int k) {
  ull res = 1;
  if (k > n - k) {
    k = n - k;
  }
  for (int i = 0; i < k; i++) {
    res *= (n - i);
    res /= (i + 1);
  }
  return res;
}

ull catalan(int n) {
  ull c = binomial(2*n, n);
  // return 2nCn / (n + 1)
  return c / (n + 1);
}
int main()  {
  //catalan[n - 2] gives the answer for n-sided polygon
  for (int n = 3; n <= 10; n++) {
    cout << catalan(n - 2) << endl;
  }
  return 0;
}