The Journal
Practical SQL, Python, data science and AI guides, written from real practice — not just to rank.
Binary Tree in Python: Traversals Explained
Binary tree in Python explained: TreeNode class, preorder, inorder, postorder and level-order traversals, height, leaves and path sum,…
Linked List in Python: Singly and Doubly
Linked list in Python explained: Node class, singly and doubly linked lists, reverse, find the middle and detect…
Queue and Deque in Python Explained
Queue in Python explained: why deque beats list.pop(0), a Queue class, BFS, sliding window maximum and round-robin, with…
Stack in Python: Implementation and Uses
Stack in Python explained: push, pop and peek with a list or class, plus brackets, undo, postfix and…
Hash Tables in Python: Dict and Set for DSA
Hash tables in Python explained: how dict and set work, hashing and collisions, and the counting, two-sum and…
Sliding Window Technique in Python
Sliding window technique in Python with real code: fixed and variable windows, longest unique substring, smallest subarray sum…
Two Pointers Technique in Python
Two pointers technique in Python with real code: two-sum on a sorted list, palindromes, removing duplicates and merging,…
Time Complexity of Python Data Structures
Time complexity of Python data structures: cost of list, dict, set, deque and heapq operations, with short runnable…
Big O Notation Explained With Python Examples
Big O notation explained simply with Python examples: O(1), O(n), O(log n), O(n^2) and O(2^n), with real step…