Staff Engineer & Algorithmic Specialist
Elena Rostova is a Staff Software Engineer and competitive programming mentor based in Toronto. She specializes in graph theory, dynamic programming optimization, and preparing engineering candidates for top tech company technical interviews across Canada and the US.
Learn how to validate a Binary Search Tree (BST) using Depth-First Search (DFS) with lower and upper value bounds in O(N) time complexity.
Detailed mathematical breakdown of QuickSort O(N log N) average time vs MergeSort O(N log N) space trade-offs in modern memory architectures.
Comprehensive guide to implementing binary search cleanly, avoiding infinite loops, overflow errors with mid calculation, and finding lower/upper bounds.
Learn how to solve the classic 0/1 Knapsack problem using dynamic programming tabular method in O(N * W) time and space complexity.
Compare Min-Heap O(N log K) time solution with Bucket Sort O(N) linear time approach for finding K most frequent array elements.
Master the Sliding Window and Two-Pointer algorithmic techniques to reduce O(N^2) nested loops to O(N) linear time complexity.