1
var numTrees = function (n) {
2
  // Create 'sol' array to store the solution...
3
  var sol = [1, 1];
4
  // Run a loop from 2 to n...
5
  for (let i = 2; i <= n; i++) {
6
    sol[i] = 0;
7
    // Within the above loop, run a nested loop from 1 to i...
8
    for (let j = 1; j <= i; j++) {
9
      // Update the i-th position of the array by adding the multiplication of the respective index...
10
      sol[i] += sol[i - j] * sol[j - 1];
11
    }
12
  }
13
  // Return the value of the nth index of the array to get the solution...
14
  return sol[n];
15
};