Coding Problem : Concatenation of Array — Brute Force in JS

Concatenation of Array. Easy on paper. But this isn't a toy problem — Google, Meta, Amazon, Adobe, and OpenAI all ask it. In this Part 1, I walk the brute force the way I want a new programmer to see it: problem → analogy → flow chart → JavaScript line by line → algorithm trace → complexity → the two traps every beginner falls into. This is Part 1 of 2. Part 2 covers the one-loop modulo trick that shows up across at least a dozen array problems — subscribe so you don't miss it. CHAPTERS 0:00 Cold open 0:15 Companies that ask this 0:30 Problem + worked examples 1:10 Constraints + pause 1:40 Photocopier analogy 2:00 Algorithm flow chart 2:35 Pseudocode 3:10 JavaScript, line by line 4:30 Why the offset works 5:10 Example 1 traced 6:00 Complexity 6:30 Two traps 7:10 Why Part 2 is better 7:30 Recap + outro KEY TAKEAWAYS → Size output up front: const ans = new Array(2 * n) → The offset shift writes into the second half from a 0..n-1 loop → Time O(n) · Auxiliary space O(1) → Trap: JS returns undefined silently on out-of-bounds — meaner than Java → Trap: forgetting the offset overwrites the first half — bug ships clean 📚 Playlist: Coding Problems Decoded — One Pattern at a Time 📌 Topic: Coding Problems — Arrays & Two Pointers #CodingProblems #CodingProblem #Arrays #DSA #JavaScript #Codebrainery