Micro-Drill #198 — Recursive vs iterative tree traversal tradeoffs

RECURSIVE vs ITERATIVE TRAVERSAL
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RECURSIVE:                    ITERATIVE:
  + Clean, readable             + No stack overflow risk
  + Natural for trees           + Can pause/resume
  - Python recursion limit      + O(1) extra space (Morris)
  - Stack frame overhead        - More complex code

WHEN TO USE ITERATIVE:
  □ Deep trees (>1000 nodes) → recursion limit
  □ Need to process nodes in specific order with state
  □ Morris traversal needed (O(1) space)
  □ Interview asks for iterative explicitly

CONVERSION PATTERN:
  Recursive → Iterative:
  1. Create explicit stack
  2. Push root
  3. While stack not empty:
     - Pop node
     - Process it (preorder) or push for later (inorder)
     - Push children (right first, then left for preorder)

MORRIS TRAVERSAL: O(1) space
  Uses threaded tree (temporary right pointers)
  Only for inorder/preorder