Fix Dutch National Flag flashcards to match book solution and clarify stack optimization question

Author: Brian Elinsky

problem-questions/05_arrays/5.01_dutch_national_flag/01_what_each_pointer_represents.md

@@ -5,4 +5,4 @@
 **A:**
 - `smaller`: first position of middle region (= pivot)
 - `equal`: first unprocessed element
-- `larger`: last unprocessed element (NOT first position of top region)
+- `larger`: first position of top region (boundary after unprocessed)

problem-questions/05_arrays/5.01_dutch_national_flag/02_initialize_pointers.md

@@ -5,4 +5,4 @@
 **A:**
 - `smaller = 0` (middle region starts empty at beginning)
 - `equal = 0` (first element is unprocessed)
-- `larger = len(A) - 1` (last index, top region built from right)
+- `larger = len(A)` (top region starts empty, built from right)

problem-questions/08_stacks_and_queues/8.01_stack_with_max/00_optimization_strategy_for_slow_operations.md

@@ -1,5 +1,7 @@
 # Optimization Strategy for Slow Operations
 
-**Q:** When a data structure operation is too slow (e.g., O(n) max lookup), what's the first optimization strategy?
+**Q:** When augmenting a data structure with a new operation that would otherwise be slow (e.g., O(n) max on a stack), what's the key strategy?
 
 **A:** Cache/precompute the result using auxiliary space. Trade space for time.
+
+Note: This applies when you're constrained to a particular data structure but need to add an operation. If you can change the data structure entirely, consider using a more suitable one instead.