My data structures exam contains the following question:
Which of the statements below about red-black trees is true? (select one or more)
- Every path from the root to a leaf has the same amount of red links.
- A node never has two red links to his childs.
- Using a red-black tree, you can always draw the associated 2-3 tree.
- All leafs of a red-black tree are at the same height.
The correct answer is: 2 and 3.
I don't understand why a node can never have two red links to his child. On the image below (from Wikipedia), I can see two red childs at node 25.
Could someone explain this to me?