Compute the Diameter of an Undirected Tree
Company: Qualcomm
Role: Software Engineer
Category: Coding & Algorithms
Difficulty: medium
Interview Round: Technical Screen
# Compute the Diameter of an Undirected Tree
You are given an undirected tree with nodes numbered from `0` through `n - 1`. The **diameter** is the number of edges on the longest simple path between any two nodes.
Return the tree's diameter.
## Function Signature
```python
def tree_diameter(n: int, edges: list[list[int]]) -> int:
...
```
## Input and Output
- Each element of `edges` is `[u, v]` and represents one undirected edge.
- Return the maximum number of edges on any simple path.
## Constraints
- `1 <= n <= 100_000`
- `len(edges) == n - 1`
- `0 <= u, v < n` and `u != v`
- The input graph is connected and contains no cycle.
## Examples
```text
Input: n = 5, edges = [[0, 1], [1, 2], [1, 3], [3, 4]]
Output: 3
```
```text
Input: n = 1, edges = []
Output: 0
```
Quick Answer: Compute the diameter of a large undirected tree, measured by the number of edges on its longest simple path. The exercise tests adjacency construction, linear-time tree traversal, endpoint reasoning, recursion-depth awareness, and edge cases such as a single-node tree.