42 lines
1.5 KiB
Markdown
42 lines
1.5 KiB
Markdown
## Outline
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- Review tree rotations and red-black trees
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- Properties of a red-black tree
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- Top (root) node is black
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- The children and parent of a red node are black
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- Null nodes are colored black
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- The path from any particular node to a null node must contain the
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same number of black nodes
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- Dive into the steps for rebalancing a red-black tree
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Also see the accompanying whiteboard pictures.
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## Assignment
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**Clarifications on the red-black tree example:**
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- In your assignment, you should first color a node _red_ when inserting it.
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- Then, check for red-red violations (the second rule). Then, rebalance if necessary.
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- If the uncle of the inserted node (parent → parent → right child) is red,
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you'll want to do two things:
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- Color the parent, uncle, and grandparent in a way which preserves all the rules
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(which ones are colored which, are an exercise left to you)
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- _Recursively_ run the rebalancing algorithm on the grandparent
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- Otherwise, your task is to figure out the correct conditions in which
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each of the rebalancing algorithms apply.
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Copy 2026.07.01/homework.py into your own [Git repository](https://gitea.bchen.dev/ethan/dsa-homework),
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with a new folder for the date. Implement the `rebalance_from_just_inserted`
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function.
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Don't change the test cases, but use them to inform how you implement your
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code. Try to pass all the test cases.
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Follow the instructions from last session (2026.06.12) to commit and push
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your changes to Gitea.
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