#coding-test articles

EJEJ Jungejjung.hashnode.devAug 22, 2025 · 3 min read

A Beginner's Guide to Trees

1. Introduction to Trees A Tree is a widely used data structure in computer science that simulates a hierarchical tree structure with a set of connected nodes. Unlike linear data structures such as arrays or linked lists, trees allow efficient repres...

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EJEJ Jungejjung.hashnode.devAug 21, 2025 · 7 min read

A Beginner's Guide to Linked List

1. Introduction to Linked Lists A Linked List is a linear data structure where elements, called nodes, are connected using pointers. Unlike arrays, linked lists do not require contiguous memory, making insertion and deletion operations efficient. Eac...

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EJEJ Jungejjung.hashnode.devAug 21, 2025 · 4 min read

A Beginner's Guide to Binary Search Algorithm

1. Introduction to Binary Search Binary Search is one of the most fundamental algorithms in computer science. It is a highly efficient method to find the position of a target value within a sorted array. Instead of scanning the entire array linearly,...

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EJEJ Jungejjung.hashnode.devAug 12, 2025 · 2 min read

A Guide to Minimum Spanning Trees: Kruskal's vs. Prim's Algorithm

Minimum Spanning Tree (MST) A Minimum Spanning Tree of a connected, undirected, weighted graph is a subset of edges that: Connects all vertices without cycles. Has the minimum possible total edge weight. 1. Kruskal’s Algorithm Idea: Kruskal’s al...

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EJEJ Jungejjung.hashnode.devAug 8, 2025 · 2 min read

Understanding DFS and BFS Techniques

This note summarizes essential techniques and patterns when solving BFS/DFS problems, especially in grid-based problems and graph traversal. Many of these ideas come up repeatedly in coding interviews or contest problems. 🚩 General DFS Rules Alway...

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EJEJ Jungejjung.hashnode.devJul 15, 2025 · 3 min read

A Beginner's Guide to the Union-Find

Union-Find, also known as Disjoint Set Union (DSU), is a data structure that efficiently keeps track of a set of elements partitioned into disjoint (non-overlapping) subsets. It's particularly useful in problems involving connectivity, such as determ...

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EJEJ Jungejjung.hashnode.devJul 7, 2025 · 3 min read

A Beginner's Guide to the Sliding Window

Sliding Window is one of the most efficient and elegant techniques used in solving problems involving arrays or strings. Especially useful when you're dealing with subarrays or substrings, it allows y

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EJEJ Jungejjung.hashnode.devJul 3, 2025 · 2 min read

A Beginner's Guide to the Two Pointers

📌 1. What is Two Pointers? The Two Pointers technique uses two variables (usually indices) to traverse a list or string from different directions (e.g., start and end).By controlling the movement of these pointers, you can solve problems more effici...

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EJEJ Jungejjung.hashnode.devJun 18, 2025 · 2 min read

Key Sorting Algorithms Every Coder Should Know - 1

🫧 1. Bubble Sort Compare adjacent pairs of elements in an array and swap them if they are in the wrong order, gradually moving larger elements to the end of the array. 1.1. Time Complexity Average / Worst case: O(n^2) Best case: O(n) (already so...

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EJEJ Jungejjung.hashnode.devJun 16, 2025 · 3 min read

Big-O You Actually Need to Know (Nothing More)

If you’re preparing for coding interviews, you’ve probably heard about Big-O notation more times than you can count. But let’s be honest—most of us don’t need to memorize every complexity out there. What you do need is a solid grasp of the core conce...

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