docs: Add 900+ comprehensive Python exercises

- Created 3 parts with 900+ exercises covering all Python topics
- Part 1: Basic syntax, operators, control flow, loops, functions, strings (260 exercises)
- Part 2: Lists, tuples, sets, dicts, file handling, OOP, errors, modules (270 exercises)
- Part 3: Advanced topics, projects, DSA, web scraping, database, API, testing (370 exercises)
- Each exercise has clear problem statement and difficulty level
- Organized by topic with progressive difficulty (Easy → Medium → Hard)
- Includes progress tracker and solution templates

Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>

Author: hackdartstorm

.github/EXERCISES/002_500_exercises_part2.md

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+# 500+ Python Exercises - Part 2
+
+## Section 7: Lists (50 exercises)
+
+### Easy (1-18)
+
+1. Create empty list and print it
+2. Create list with 5 integers
+3. Create list with mixed data types
+4. Access first element of list
+5. Access last element of list
+6. Access element at index 3
+7. Find length of list
+8. Append element to end of list
+9. Insert element at specific position
+10. Remove element by value
+11. Remove element by index
+12. Pop last element from list
+13. Find index of element
+14. Count occurrence of element
+15. Sort list in ascending order
+16. Sort list in descending order
+17. Reverse a list
+18. Copy a list
+
+### Medium (19-35)
+
+19. Find sum of all elements
+20. Find maximum element
+21. Find minimum element
+22. Find average of elements
+23. Count even numbers in list
+24. Count odd numbers in list
+25. Find all prime numbers in list
+26. Remove duplicates from list
+27. Merge two lists
+28. Find common elements in two lists
+29. Find difference of two lists
+30. Find intersection of two lists
+31. Find union of two lists
+32. Rotate list by n positions
+33. Find second largest element
+34. Find second smallest element
+35. Move zeros to end of list
+
+### Hard (36-50)
+
+36. Find majority element (> n/2 occurrences)
+37. Find missing number in sequence 1-n
+38. Find duplicate in array
+39. Find pair with given sum
+40. Find triplet with given sum
+41. Find maximum subarray sum (Kadane's)
+42. Find product of array except self
+43. Find leaders in array
+44. Find trapping rainwater
+45. Find maximum profit from stock prices
+46. Implement two stacks in one list
+47. Find equilibrium index
+48. Find pivot index
+49. Sort array of 0s, 1s, 2s (Dutch flag)
+50. Find kth largest element
+
+---
+
+## Section 8: Tuples & Sets (40 exercises)
+
+### Tuples (1-20)
+
+1. Create empty tuple
+2. Create tuple with 5 elements
+3. Create tuple with single element
+4. Access tuple element by index
+5. Find length of tuple
+6. Concatenate two tuples
+7. Repeat tuple n times
+8. Find index of element in tuple
+9. Count occurrence of element
+10. Find maximum in tuple
+11. Find minimum in tuple
+12. Sum all elements in tuple
+13. Convert list to tuple
+14. Convert tuple to list
+15. Unpack tuple into variables
+16. Create nested tuple
+17. Access nested tuple elements
+18. Find hash of tuple
+19. Check if element exists in tuple
+20. Slice a tuple
+
+### Sets (21-40)
+
+21. Create empty set
+22. Create set with elements
+23. Add element to set
+24. Remove element from set
+25. Discard element from set
+26. Pop element from set
+27. Clear all elements from set
+28. Find length of set
+29. Check if element exists in set
+30. Find union of two sets
+31. Find intersection of two sets
+32. Find difference of two sets
+33. Find symmetric difference
+34. Check if set is subset
+35. Check if set is superset
+36. Check if sets are disjoint
+37. Add multiple elements to set
+38. Update set with another set
+39. Find set comprehension
+40. Remove duplicates from list using set
+
+---
+
+## Section 9: Dictionaries (50 exercises)
+
+### Easy (1-18)
+
+1. Create empty dictionary
+2. Create dictionary with key-value pairs
+3. Access value by key
+4. Add new key-value pair
+5. Update value of existing key
+6. Remove key-value pair
+7. Find length of dictionary
+8. Check if key exists
+9. Get all keys
+10. Get all values
+11. Get all key-value pairs
+12. Get value with default
+13. Copy dictionary
+14. Clear dictionary
+15. Create dictionary from keys
+16. Create dictionary from values
+17. Merge two dictionaries
+18. Find key with maximum value
+
+### Medium (19-35)
+
+19. Find key with minimum value
+20. Sort dictionary by keys
+21. Sort dictionary by values
+22. Count frequency of elements using dict
+23. Invert dictionary (keys become values)
+24. Find common keys in two dicts
+25. Find difference of keys
+26. Group elements by key
+27. Filter dictionary by value
+28. Map dictionary values
+29. Create nested dictionary
+30. Access nested dictionary
+31. Flatten nested dictionary
+32. Convert two lists to dictionary
+33. Convert dictionary to list of tuples
+34. Find top 3 values
+35. Find top 3 keys
+
+### Hard (36-50)
+
+36. Implement LRU cache using dict
+37. Find anagrams grouping
+38. Find word frequency in text
+39. Implement phone book
+40. Implement inventory system
+41. Find pairs with given sum
+42. Find longest chain of pairs
+43. Implement trie using nested dicts
+44. Find shortest path in graph
+45. Count connected components
+46. Implement hash map
+47. Find majority element
+48. Find k most frequent elements
+49. Find minimum window substring
+50. Implement autocomplete system
+
+---
+
+## Section 10: File Handling (40 exercises)
+
+### Easy (1-15)
+
+1. Create new text file
+2. Write text to file
+3. Read entire file content
+4. Read file line by line
+5. Read first n lines
+6. Read last n lines
+7. Append text to file
+8. Copy file content to another file
+9. Count lines in file
+10. Count words in file
+11. Count characters in file
+12. Find longest word in file
+13. Find shortest word in file
+14. Search for word in file
+15. Replace word in file
+
+### Medium (16-30)
+
+16. Count frequency of each word
+17. Remove duplicate lines
+18. Sort lines alphabetically
+19. Reverse content of file
+20. Merge two files
+21. Split file into n parts
+22. Find common words in two files
+23. Create log file parser
+24. Read CSV file
+25. Write to CSV file
+26. Read JSON file
+27. Write to JSON file
+28. Find file size
+29. Check if file exists
+30. Get file creation/modification time
+
+### Hard (31-40)
+
+31. Implement file compression
+32. Implement file encryption
+33. Create backup system
+34. Find duplicate files
+35. Search file in directory
+36. Batch rename files
+37. Organize files by extension
+38. Create file indexer
+39. Implement tail -f command
+40. Parse large file efficiently
+
+---
+
+## Section 11: OOP (60 exercises)
+
+### Easy (1-20)
+
+1. Create simple class with attributes
+2. Create class with methods
+3. Create constructor __init__
+4. Create __str__ method
+5. Create __repr__ method
+6. Create class with private attributes
+7. Create getter method
+8. Create setter method
+9. Create class variable
+10. Create instance variable
+11. Create static method
+12. Create class method
+13. Create property decorator
+14. Create setter decorator
+15. Create deleter decorator
+16. Inherit from parent class
+17. Override parent method
+18. Use super() function
+19. Check instance type
+20. Check class inheritance
+
+### Medium (21-40)
+
+21. Implement multiple inheritance
+22. Implement multilevel inheritance
+23. Implement hierarchical inheritance
+24. Implement hybrid inheritance
+25. Create abstract base class
+26. Implement interface
+27. Implement operator overloading (+)
+28. Implement operator overloading (-)
+29. Implement operator overloading (==)
+30. Implement operator overloading (<)
+31. Implement __len__ method
+32. Implement __iter__ method
+33. Implement __next__ method
+34. Implement __call__ method
+35. Implement __getitem__ method
+36. Implement __setitem__ method
+37. Implement __delitem__ method
+38. Implement context manager
+39. Implement descriptor
+40. Implement weak reference
+
+### Hard (41-60)
+
+41. Implement singleton pattern
+42. Implement factory pattern
+43. Implement observer pattern
+44. Implement strategy pattern
+45. Implement decorator pattern
+46. Implement adapter pattern
+47. Implement facade pattern
+48. Implement proxy pattern
+49. Implement command pattern
+50. Implement state pattern
+51. Implement template method pattern
+52. Implement iterator pattern
+53. Implement composite pattern
+54. Implement builder pattern
+55. Implement prototype pattern
+56. Implement flyweight pattern
+57. Implement chain of responsibility
+58. Implement mediator pattern
+59. Implement memento pattern
+60. Implement visitor pattern
+
+---
+
+## Section 12: Error Handling (30 exercises)
+
+### Easy (1-12)
+
+1. Handle ZeroDivisionError
+2. Handle ValueError
+3. Handle TypeError
+4. Handle IndexError
+5. Handle KeyError
+6. Handle FileNotFoundError
+7. Handle multiple exceptions
+8. Use else clause
+9. Use finally clause
+10. Raise exception manually
+11. Create custom exception
+12. Chain exceptions
+
+### Medium (13-22)
+
+13. Validate email with exception
+14. Validate phone with exception
+15. Validate age with exception
+16. Create validation exception hierarchy
+17. Handle file operation errors
+18. Handle database errors
+19. Handle API request errors
+20. Handle JSON parsing errors
+21. Handle network timeout
+22. Retry on failure
+
+### Hard (23-30)
+
+23. Implement transaction rollback
+24. Create error logging system
+25. Implement circuit breaker
+26. Create custom exception framework
+27. Handle async errors
+28. Implement error recovery
+29. Create fault-tolerant system
+30. Implement graceful degradation
+
+---
+
+## Section 13: Modules & Packages (30 exercises)
+
+### Easy (1-12)
+
+1. Create simple module
+2. Import module
+3. Import specific function
+4. Import with alias
+5. Import all from module
+6. Create package with __init__.py
+7. Import from package
+8. Use relative import
+9. Use absolute import
+10. Create submodule
+11. Use if __name__ == "__main__"
+12. Create module documentation
+
+### Medium (13-22)
+
+13. Create utility module
+14. Create math module
+15. Create string module
+16. Create file operations module
+17. Create date/time module
+18. Use built-in random module
+19. Use built-in math module
+20. Use built-in datetime module
+21. Use built-in collections module
+22. Use built-in itertools module
+
+### Hard (23-30)
+
+23. Create pip-installable package
+24. Add package to PyPI
+25. Create module with C extension
+26. Use importlib for dynamic import
+27. Create module loader
+28. Implement plugin system
+29. Create namespace package
+30. Implement module versioning
+
+---
+
+*Continued in Part 3...*