posts: treap-revisited: add insertion

This commit is contained in:
Bruno BELANYI 2024-07-27 18:32:47 +01:00
parent 0798812f86
commit 652fe81c41

View file

@ -103,3 +103,28 @@ def merge(
return right
raise RuntimeError("Unreachable")
```
### Insertion
Inserting a node into the tree is done in two steps:
1. `split` the tree to isolate the middle insertion point
2. `merge` it back up to form a full tree with the inserted key
```python
def insert(self, key: K, value: V) -> bool:
# `left` and `right` come before/after the key
left, node, right = split(self._root, key)
was_updated: bool
# Create the node, or update its value, if the key was already in the tree
if node is None:
node = Node(key, value)
was_updated = False
else:
node.value = value
was_updated = True
# Rebuild the tree with a couple of merge operations
self._root = merge(left, merge(node, right))
# Signal whether the key was already in the key
return was_updated
```