Q-13. Recursive binary tree code. Write a recursive C++ function called insert which takes two arguments: a pointer to the root of a binary scarch tree whose nodes are as defincd above, and an integer...

Extracted text: Q-13. Recursive binary tree code. Write a recursive C++ function called insert which takes two arguments: a pointer to the root of a binary scarch tree whose nodes are as defincd above, and an integer key. The function inscrts a new key into the tree and returns a pointer to the node. The tree should only store unique keys. When a duplicate key is encountered, the function increments the appropriate node count variable and returns a pointer to the node.