Definition
Postorder traversal visits nodes in Left subtree -> Right subtree -> Root order.
Key Characteristics
- ✓Visit parent after all children are processed
- ✓Root is visited last
- ✓A form of DFS (Depth-First Search)
Use Cases
Used in these scenarios:
🗑️
Tree Deletion
Delete children first for safe tree removal
🧮
Expression Tree Postfix
Generate postfix notation (reverse Polish)
📁
Directory Size Calc
Calculate subfolder sizes before parent
Complexity
Time Complexity
Best
O(N)
Average
O(N)
Worst
O(N)
Space Complexity
O(H)
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