Breaking down the state transitions for the classic 0/1 Knapsack DP problem with bottom-up tabulation.

Building an O(1) LRU Cache using Hash Map + Doubly Linked List — a top system design/coding interview question.

Traversing a binary tree level-by-level using a queue — fundamental for shortest-path problems.

In-place reversal of a singly linked list — mastering this requires truly understanding pointers.

Finding LCA in a BST vs a general Binary Tree using DFS — two elegant recursive algorithms.

Sort intervals by start time and merge overlapping pairs — a staple for calendar/scheduling problems.

Using a stack to validate matching brackets in O(N) time — a fundamental interview pattern.

Optimizing the classic Two Sum from O(N²) brute force to O(N) using a hash map.

Finding shortest paths in a weighted graph using a Priority Queue (Min-Heap) — O((V+E) log V).