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Month 1: Programming Fundamentals and Basic Data Structures

  1. Choose a Programming Language:

    • Action: Pick a language like Python, Java, C++, or JavaScript.

    • Why? Most FAANG companies allow coding interviews in these languages. Choose one and stick with it to avoid context switching.

    • Practice: Write basic programs (e.g., printing patterns, simple calculators, sorting numbers).

  2. Mathematics for DSA:

    • Logarithms:

      • Understand why algorithms like Binary Search operate in O(log n) time.

      • Example Problems:

        • Calculate the time complexity of different search algorithms.
    • Modular Arithmetic:

      • Learn how to handle overflow and operations in modular arithmetic.

      • Example Problems:

        • Solve problems related to large number multiplication.
    • Bit Manipulation:

      • Practice basic operations (AND, OR, XOR, left/right shift).

      • Example Problems:

        • Determine if a number is a power of two.

        • Find the only non-repeating element in an array where every other element repeats twice.

  3. Arrays and Strings:

    • Arrays:

      • Learn about indexing, slicing, insertion, and deletion.

      • Understand how arrays are stored in memory.

      • Example Problems:

        • Rotate an array by k steps.

        • Find the contiguous subarray with the largest sum (Kadane's Algorithm).

    • Strings:

      • Learn string operations (concatenation, slicing, pattern matching).

      • Example Problems:

        • Implement strStr() (needle in a haystack).

        • Reverse a string.

  4. Introduction to Recursion:

    • Recursion Basics:

      • Learn how recursive functions work and when to use them.

      • Understand the base case and recursive case.

      • Example Problems:

        • Generate all subsets of a set.

        • Calculate factorials using recursion.


Month 2: Fundamental Data Structures and Basic Algorithms

  1. Linked Lists:

    • Singly and Doubly Linked Lists:

      • Learn how to implement singly and doubly linked lists.

      • Understand common operations: insertion, deletion, searching, and reversal.

      • Example Problems:

        • Merge two sorted linked lists.

        • Remove nth node from the end of the linked list.

    • Circular Linked Lists:

      • Learn about circular linked lists and their uses.

      • Example Problems:

        • Detect the start of a cycle in a circular linked list.
  2. Stacks and Queues:

    • Stacks:

      • Understand the LIFO (Last In, First Out) principle.

      • Learn how to implement a stack using arrays and linked lists.

      • Example Problems:

        • Evaluate a postfix expression.

        • Implement a function to check balanced parentheses in an expression.

    • Queues:

      • Understand the FIFO (First In, First Out) principle.

      • Implement a queue using arrays and linked lists.

      • Example Problems:

        • Implement a queue using two stacks.

        • Design a circular queue.

  3. Hashing (Hash Tables/Hash Maps):

    • Hash Maps:

      • Learn about hash functions, collisions, and collision resolution techniques.

      • Understand the importance of hashing in fast data retrieval.

      • Example Problems:

        • Implement a hash map from scratch.

        • Count the frequency of characters in a string using a hash map.

        • Group anagrams from a list of strings.

  4. Basic Sorting and Searching Algorithms:

    • Sorting Algorithms:

      • Understand and implement Bubble Sort, Selection Sort, Insertion Sort, Merge Sort, Quick Sort.

      • Learn their time and space complexities.

      • Example Problems:

        • Sort an array using Quick Sort.

        • Find the Kth largest element using Quick Select.

    • Searching Algorithms:

      • Learn Linear Search and Binary Search.

      • Example Problems:

        • Find the square root of a number using Binary Search.

        • Search for a range in a sorted array.


Month 3: Intermediate Data Structures

  1. Trees:

    • Binary Trees:

      • Understand binary trees, binary search trees (BST), and their properties.

      • Learn about tree traversal methods: Inorder, Preorder, Postorder, Level Order.

      • Example Problems:

        • Find the height of a binary tree.

        • Serialize and deserialize a binary tree.

    • Binary Search Trees (BST):

      • Understand insertion, deletion, and search operations in a BST.

      • Example Problems:

        • Check if a binary tree is a BST.

        • Convert a sorted array into a balanced BST.

  2. Heaps and Priority Queues:

    • Min-Heaps and Max-Heaps:

      • Learn how heaps work and how to implement a heap using arrays.

      • Understand the use of heaps in priority queues.

      • Example Problems:

        • Find the Kth smallest/largest element in an array using a heap.

        • Implement a median finder using heaps.

  3. Advanced Recursion and Backtracking:

    • Backtracking:

      • Learn backtracking techniques and understand how to solve constraint satisfaction problems.

      • Example Problems:

        • Solve the N-Queens problem.

        • Generate all permutations of a string.

  4. Graph Basics:

    • Graph Representations:

      • Learn about different graph representations: adjacency matrix, adjacency list.

      • Understand graph traversal algorithms: Depth-First Search (DFS), Breadth-First Search (BFS).

      • Example Problems:

        • Implement DFS and BFS.

        • Find the number of connected components in a graph.


Month 4: Advanced Data Structures and Algorithms

  1. Tries (Prefix Trees):

    • Trie Data Structure:

      • Learn how to implement a trie and understand its applications in searching and prefix matching.

      • Example Problems:

        • Implement auto-complete functionality.

        • Find the longest common prefix.

  2. Dynamic Programming (DP):

    • Dynamic Programming Concepts:

      • Understand memoization (top-down approach) and tabulation (bottom-up approach).

      • Learn to recognize overlapping subproblems and optimal substructure.

      • Example Problems:

        • Solve problems like Fibonacci sequence, Longest Increasing Subsequence, and Knapsack Problem.

        • Coin Change Problem (minimum coins required).

        • Minimum Edit Distance between two strings.

  3. Greedy Algorithms:

    • Greedy Techniques:

      • Understand how to solve optimization problems using a greedy approach.

      • Example Problems:

        • Activity Selection Problem (select maximum number of non-overlapping intervals).

        • Minimum number of platforms required for a train station.

  4. Graph Algorithms (Advanced):

    • Advanced Graph Algorithms:

      • Study Dijkstra’s for shortest path, Bellman-Ford for shortest paths with negative weights, Floyd-Warshall for all-pairs shortest paths.

      • Example Problems:

        • Implement Dijkstra’s algorithm for finding the shortest path.

        • Find the minimum spanning tree using Prim’s and Kruskal’s algorithms.


Month 5: Advanced Problem-Solving and Competitive Programming

  1. Segment Trees and Fenwick Trees (Binary Indexed Trees):

    • Advanced Tree Structures:

      • Learn how to use segment trees and Fenwick trees for range queries.

      • Example Problems:

        • Range Sum Query using Segment Tree.

        • Point updates and range queries using Fenwick Tree.

  2. Disjoint Set Union (Union-Find):

    • Union-Find Data Structure:

      • Understand the union-find algorithm, including union by rank and path compression for efficient merging and finding.

      • Example Problems:

        • Find connected components in a graph.

        • Implement Kruskal’s algorithm for finding the Minimum Spanning Tree.

  3. Advanced Graph Problems:

    • Max Flow Algorithms:

      • Study the Ford-Fulkerson algorithm for computing maximum flow in a flow network.

      • Example Problems:

        • Max Flow problem using Ford-Fulkerson.

        • Finding strongly connected components using Kosaraju's or Tarjan’s algorithm.

  4. Practice Real Interview Problems:

    • Targeted Practice:

      • Use platforms like LeetCode, HackerRank, Codeforces, and InterviewBit.

      • Solve problems labeled "Top Interview Questions" or "FAANG Interview Questions."

      • Example Problems:

        • Rotate image by 90 degrees.

        • Find the first missing positive integer in an unsorted array.


Month 6: Mock Interviews and Optimization Techniques

  1. Mock Interviews:

    • Simulated Interviews:

      • Practice mock interviews with peers or online platforms like Pramp.

      • Record yourself explaining your thought process and solutions.

    • Focus Areas:

      • Practice explaining the time and space complexity of your solutions.

      • Work on articulating your approach clearly and concisely.

  2. Time and Space Complexity Analysis:

    • Complexity Analysis:

      • Master Big O notation and analyze your code for time and space complexity.

      • Optimize your solutions by reducing unnecessary operations or memory usage.

    • Example Problems:

      • Optimize algorithms for time complexity.

      • Reduce memory usage for large data sets.

  3. System Design Basics:

    • System Design Concepts:

      • Learn about designing scalable systems.

      • Understand concepts like load balancing, caching, sharding, and database optimization.

    • Example Problems:

      • Design a URL shortening service (like bit.ly).

      • Design an online chat system.

  4. Revision and Review:

    • Revising Key Concepts:

      • Review key algorithms and data structures.

      • Revisit the problems that were most challenging.

    • Final Preparation:

      • Ensure that you are comfortable with a wide range of problems.

      • Refine your ability to solve problems within the time constraints typical of coding interviews.


Additional Tips for Success:

  • Daily Practice: Aim to solve at least 2-3 problems daily to build and maintain your momentum.

  • Participate in Contests: Join coding competitions on Codeforces, AtCoder, and LeetCode to test your skills under time pressure.

  • Stay Consistent: Consistency is key; even if you miss a day, make up for it the next day to maintain a steady learning curve.

This detailed roadmap should give you a comprehensive guide to prepare for FAANG-level interviews, with specific focus areas, example problems, and step-by-step milestones!

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