Can a binary search tree contain negative numbers?

You can have any comparable values inside of a binary search tree. If it's not comparable already, you can use operator overloading in C++, or anything similar for other languages to make your values comparable. read more

A binary search tree can contain any elements belonging to the same totally ordered set. In other words, you can line up the elements from least to greatest (with some elements possibly being equal). This doesn't limit it to positive whole numbers, or even numbers. read more

Traverse the tree (it doesn’t matter whether you do a pre-order, post-order or in-order traversal) and each time you come across a node that has an odd number, delete it according to the rules for deleting nodes from a binary tree. read more