nth_catalan

/**
 *    author:  Mathura Tudu
 *    created: 25.04.2020 14:06:08 IST
**/

#include <bits/stdc++.h>

using namespace std;

using ull = unsigned long long int;
const int N = 100;
vector <ull> catalan(N + 1);

int main() {
  auto calc = [&] () {
    catalan[0] = catalan[1] = 1;
    for (int i = 2; i <= N; i++) {
      catalan[i] = 0;
      for (int j = 0; j < i; j++) {
        catalan[i] += catalan[j] * catalan[i - j - 1];
      }
    }
  };
  calc();
  //catalan[n - 2] gives the answer for n-sided polygon
  for (int n = 3; n <= 10; n++) {
    cout << catalan[n - 2] << endl;
  }
  return 0;
}