$1)$ Implement the insert method for binary search trees. Do not insert duplicate

values.

$*$NOTE: IT IS ASSUMED THAT WE DO NOT ALLOW THE INSERTION OF

DUPLICATE VALUES INTO THE TREE.

A potentially useful code snippet for creating an object using a shared pointer

is given as follows.

std::shared$\_$ptr n;

n $=$ std::shared$\_$ptr$($new Node$($val$))$;

$2)$ Implement the search method for binary search trees.

$3)$ Implement isBST, a method for checking whether or not a tree is a binary

search tree.

$4)$ Implement the pre$-$order traversal method for binary search trees.