Trees
3 programs — patterns, complexity, and code
| # | Program Name | Pattern | Time | Space | Key Idea | Level |
|---|---|---|---|---|---|---|
| 1 | maxDepthBinaryTree | DFS Recursion | O(n) | O(h) | Max depth = 1 + max(left depth, right depth); base case is null → 0. | Simple |
| 2 | invertBinaryTree | DFS Recursion | O(n) | O(h) | Swap left and right children at every node recursively. | Simple |
| 3 | levelOrderTraversal | BFS | O(n) | O(n) | Process nodes level by level using a queue; snapshot queue size per level. | Middle |