[S30]Complete Precourse-2

[paridhimalviya]

Exercise_1 : Binary Search.

Exercise_2 : Quick sort.

Exercise_3 : Find Mid Point of a Singly Linked List.

Exercise_4 : Merge Sort.

Exercise_5 : Iterative Quick Sort.

[super30admin]

The student's solution demonstrates a good understanding of various data structures and algorithms, including binary search, merge sort, quick sort (both recursive and iterative versions), linked list implementations, and stack adapters. Here are some specific observations:

Strengths:

1. The implementations are generally correct and follow standard approaches for each algorithm/data structure.
2. The code is well-organized into separate files for different concepts.
3. Good use of Swift language features like generics, optionals, and inout parameters.
4. Proper handling of edge cases in most implementations (e.g., empty arrays in sorting algorithms).
5. Clear comments explaining the logic in several places.

Areas for Improvement:

1. In the BinarySearch class, the recursive version returns nil when not found while the iterative version returns -1. This inconsistency should be fixed.
2. The QuickSort implementation could benefit from choosing a better pivot (like median-of-three) to improve worst-case performance.
3. Some functions could be made more generic (e.g., MergeSort currently only works with Int arrays).
4. The LinkedListToStackAdapter implementation could be simplified by directly using the linked list's methods rather than exposing node-level operations.
5. Some variable names could be more descriptive (e.g., 'a' and 'b' in merge sort functions).
6. The .DS_Store file should not be included in the submission as it's a system file.
7. More test cases would be beneficial, especially edge cases (empty arrays, single-element arrays, etc.).

Time and Space Complexity:

1. Binary Search: O(log n) time, O(1) space (iterative) / O(log n) space (recursive due to call stack)
2. Merge Sort: O(n log n) time, O(n) space
3. Quick Sort: O(n log n) average time, O(n^2) worst-case time, O(log n) space (recursive call stack)
4. Stack using Linked List: All operations O(1) time and space
5. Mid-point of Linked List: O(n) time, O(1) space