llama34 min read
LLaMA 3 — Complete Setup and Usage Guide
Complete guide to setting up and using Meta's LLaMA 3 models locally.
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Meta
34 articles
dsa14 min read
Two Sum — The Problem That Unlocks Every HashMap Interview Question
Two Sum is the #1 most-asked interview problem at Google, Amazon, and Meta — confirmed in over 170 interviews at 70 companies. But it is not about the solution. It is about showing you can trade space for time, recognize the hashmap complement pattern, and handle every follow-up a senior engineer can throw at you.
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dsa15 min read
Maximum Subarray — Kadane's Algorithm Explained (The Right Way) [Google, Amazon, Meta]
Most explanations of Kadane's Algorithm get it subtly wrong. Learn the correct mental model, the critical reset-to-0 bug that trips everyone up, a full visual dry run, divide-and-conquer alternative, and every FAANG follow-up question with approach hints.
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dsa12 min read
Merge Sorted Array — Why Merging From the Back Is the Elegant O(1) Solution
Most candidates try to merge nums1 and nums2 from the front and run into a subtle overwrite bug. Learn why starting from the back is the key insight, how three pointers keep the logic clean, and how this same trick powers the merge step in Merge Sort. Full Python and JavaScript solutions included.
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dsa13 min read
Single Number — XOR Bit Trick O(n) Time O(1) Space [Meta / Amazon Classic]
Find the one element that appears once while every other appears twice. The XOR bit trick delivers O(n) time and O(1) space — no extra memory, no sorting. Master the three XOR properties that make it work, then see how interviewers escalate to Single Number II and III.
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dsa2 min read
Reverse String — Two Pointer In-Place O(n) [Meta, Microsoft Easy]
Reverse a character array in-place using two pointers. O(n) time, O(1) space. The fundamental two-pointer swap pattern.
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dsa13 min read
Valid Palindrome — Two Pointer Skip Non-Alphanumeric [Meta Easy]
Master LeetCode 125 — Valid Palindrome with the O(1)-space two-pointer technique. Learn why every FAANG loop starts here, visualize the pointer walk on a classic example, avoid the four most common pitfalls, and unlock the palindrome follow-up chain: LC 680, LC 5, and LC 647.
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dsa14 min read
Missing Number — 4 Approaches, XOR Deep Dive & Interview Trade-offs [LC 268]
LeetCode 268 hides four distinct valid solutions behind a deceptively simple problem. Learn Sort, HashSet, Gauss Formula, and XOR — understand exactly why each exists, when interviewers ask for each one, and why XOR is the most elegant answer in the room.
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dsa2 min read
Find All Numbers Disappeared in Array — Index Negation O(n) O(1) [Meta Easy]
Find all integers in [1,n] missing from array of length n using O(n) time O(1) extra space via index negation.
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dsa2 min read
Max Consecutive Ones III — Sliding Window with K Flips [Google, Meta Medium]
Find maximum consecutive ones if you can flip at most k zeros to one. Variable sliding window O(n) solution.
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dsa14 min read
3Sum — The Deduplication Problem Every FAANG Interviewer Loves [LC 15]
Learn why 3Sum is a FAANG interview staple — how sorting enables two pointers, why deduplication trips up even strong candidates, a full visual dry run, and every common bug explained with Python and JavaScript solutions.
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dsa15 min read
Container With Most Water — Greedy Two-Pointer Proof [Google, Amazon, Meta]
LeetCode 11 explained from scratch: why this is a greedy problem, the formal proof that you must always move the shorter pointer, a full step-by-step dry run, common traps, and clean Python + JavaScript solutions. Master the pointer-elimination pattern that appears throughout FAANG interviews.
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dsa15 min read
Product of Array Except Self — The Prefix × Suffix Trick That Google Loves
LeetCode 238 is one of the most frequently asked medium problems at Google and Meta. Learn why the no-division constraint is intentional, how the prefix × suffix insight unlocks the O(n) solution, and how a single running variable eliminates the extra O(n) space entirely.
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dsa12 min read
Merge Intervals — The Definitive Guide (LeetCode 56) [Google, Meta, Amazon, Microsoft]
Master the classic Merge Intervals problem (LeetCode 56) asked at Google, Meta, Amazon, and Microsoft. Learn why sorting by start time is the key insight, the exact overlap condition (c ≤ b), a step-by-step visual dry run, 4 common mistakes, Python and JavaScript solutions, and follow-up problems including Insert Interval, Non-overlapping Intervals, and Meeting Rooms II.
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dsa13 min read
Group Anagrams — Hashmap Key Design Mastery [Amazon, Google, Meta]
Group strings that are anagrams of each other using two canonical approaches: sorted string key O(n·k·log k) and character frequency tuple key O(n·k). Understand when the difference matters, trace through a dry run, dodge the common traps, and leave any interview with both solutions ready to go.
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dsa13 min read
Longest Substring Without Repeating Characters — Sliding Window [Google, Amazon, Meta]
Master LeetCode 3 — the canonical sliding window problem. Understand the "shrink from left" insight, the critical stale-index bug with max(), and both set-based and hashmap-optimized solutions in Python and JavaScript. Includes a full step-by-step dry run and follow-up problems LC 340 and LC 159.
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dsa13 min read
Subarray Sum Equals K — Why Prefix Sum + HashMap Beats Everything [LC 560]
LeetCode 560 is one of the most-asked FAANG problems because it teaches the prefix sum + hashmap pattern — a technique that handles negative numbers, generalizes to a dozen follow-ups, and cannot be replaced by sliding window. Learn the insight, the dry run, the common mistakes, and the O(n) solution in Python and JavaScript.
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dsa15 min read
Search in Rotated Sorted Array — The Binary Search Problem Every FAANG Interviewer Loves
LeetCode 33 is a rite of passage in FAANG interviews. Learn the one invariant that makes O(log n) possible on a rotated array, trace through a dry run, avoid the 4 most common bugs, and master the full family of follow-up problems (LC 81, LC 153, LC 154).
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dsa14 min read
Jump Game — Greedy Max Reach O(n) Explained (The Definitive Guide) [Amazon, Google, Meta]
LeetCode 55 is a classic FAANG greedy problem that tests whether you can compress O(n²) DP thinking into a single O(n) pass. Learn the "max reachable index" insight, why greedy beats DP here, a full visual dry run, common traps, and every follow-up question interviewers ask next.
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dsa13 min read
Rotate Image 90° Clockwise — Transpose + Reverse, In-Place O(n²) [Amazon, Microsoft, Google]
Learn how to rotate an n×n matrix 90° clockwise in-place using the elegant transpose-then-reverse trick. Understand the math behind it, see the 4-cell direct rotation alternative, dry-run through a worked example, avoid the four most common mistakes, and get clean Python + JavaScript solutions.
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dsa2 min read
Valid Palindrome [Easy] — Two Pointers Inward
Check if a string is a palindrome after removing non-alphanumeric characters using inward two pointers.
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dsa2 min read
String Problems — Meta and Google Favourites
High-frequency string problems from Meta and Google interviews: valid parentheses, longest substring without repeating characters, zigzag conversion, and string to integer.
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dsa3 min read
Mock Week 4 — Full Company Simulation (Google, Meta, Amazon)
Full company-specific mock sessions. Each simulation replicates the actual interview format, problem difficulty distribution, and evaluation criteria of Google, Meta, and Amazon.
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dsa3 min read
Meta Behavioral + Coding Interview Prep
Meta's interview process: core values evaluation, coding speed expectations, and preparation strategies for Meta's unique product-focused behavioral questions.
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dsa2 min read
Company-Tagged Problems — Google, Meta, Amazon Strategy Guide
Strategic guide to company-specific DSA preparation: Google's focus on graphs and DP, Meta's emphasis on arrays and trees, Amazon's leadership principles alignment with system design and BFS.
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dsa2 min read
Meta — Flatten Nested List Iterator (Stack-Based)
Implement an iterator for a nested list that flattens it lazily. Meta favors this for testing iterator design, stack usage, and lazy evaluation.
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dsa2 min read
Meta — Serialize and Deserialize Binary Tree (BFS/Preorder)
Serialize a binary tree to a string and deserialize it back. Meta loves this problem for testing tree traversal and string parsing. Both BFS and preorder DFS approaches shown.
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dsa2 min read
Meta — Read N Characters Given read4 (Buffered Read)
Implement a read() function using a read4() primitive. Two variants: read once and read multiple times. Tests buffer management and pointer arithmetic.
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dsa2 min read
Meta — Generate Parentheses (Backtracking)
Generate all combinations of well-formed parentheses of given n pairs using backtracking. Track open and close counts to prune invalid branches early.
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dsa2 min read
Meta — Subarray Sum Equals K (Prefix Sum + HashMap)
Count subarrays with sum equal to k using prefix sums and a hashmap. O(n) time by tracking how many times each prefix sum has occurred.
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dsa2 min read
Meta — Binary Tree Right Side View (BFS Level Order)
Return the values visible from the right side of a binary tree — the last node of each BFS level. O(n) BFS with level tracking.
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dsa2 min read
Meta — Accounts Merge (Union-Find on Emails)
Merge accounts sharing common email addresses using Union-Find. Group emails by owner, merge accounts with shared emails, sort each merged group.
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dsa2 min read
Meta — Clone Graph (Deep Copy with DFS/BFS + HashMap)
Create a deep copy of an undirected graph using DFS with a HashMap to track visited/cloned nodes. Meta tests this to evaluate graph traversal and pointer manipulation.
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dsa3 min read
Company Problems — Master Recap & Interview Cheatsheet
Complete recap of all 24 company-tagged problems with pattern classification, company attribution, and key insights. Use as a final review checklist before company-specific interviews.
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