Red black tree sort
Implement red-black tree sorting of fixed width integers. Here, the left branch will only contain nodes with a smaller key and the right branch will only contain nodes with a larger key.
Red black tree sort is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.
Start with an empty tree, add 30 nodes each with arbitrary (aka "random") keys, then traverse the tree, printing the values from the left node, the key value, then the values from the right node, displaying their value and their color (red or black). Since we are using a red-black tree here, this would eliminate any duplicate values.
Then delete an arbitrary 15 nodes and display the resulting tree.
You may use an implementation at Algebraic data types as a starting point, if you find that helpful.