Data Structures & Algorithms in Java

What you will be able to do

• Build linked lists, stacks, queues, trees, heaps and tries from scratch in Java
• Choose between Java's built-in collections and your own structure for a problem
• Implement and compare the main sorting algorithms
• Solve tree and graph problems with DFS, BFS, shortest paths, topological sort and union-find
• Recognise greedy and interval problems and know when greedy fails
• Turn recursive solutions into dynamic programming, from 1D to 2D

What you will learn

1. 6.1Linked Lists

   Write your own singly and doubly linked lists and solve the pointer questions interviews love.

   1. Why linked lists exist26 min
   2. Build a singly linked list28 min
   3. Insert and delete nodes30 min
   4. Reverse a linked list34 min
   5. Fast and slow pointers34 min
   6. Merge and remove problems35 min
   7. Doubly and circular linked lists24 min
   8. Design an LRU cache28 min
   9. Advanced list problems28 min
   10. Practice: linked lists35 min

2. 6.2Stacks & Queues

   Implement stacks and queues yourself and use the monotonic stack for next greater style problems.

   1. Stacks: last in, first out25 min
   2. Build a stack yourself28 min
   3. Balanced brackets25 min
   4. Queues: first in, first out25 min
   5. Build a circular queue28 min
   6. Min stack and a queue from stacks30 min
   7. Evaluating expressions30 min
   8. Monotonic stack32 min
   9. Largest rectangle in a histogram32 min
   10. Deques28 min
   11. Practice: stacks and queues32 min

3. 6.3Hash Tables from Scratch

   Build your own hash map to understand why HashMap is fast, and when it is not.

   1. How hashing works24 min
   2. Build a hash map with chaining30 min
   3. Open addressing28 min
   4. Load factor and resizing28 min
   5. Inside Java's HashMap30 min
   6. hashCode and equals in practice28 min
   7. Hashing in the real world26 min
   8. Practice: hash tables32 min

4. 6.4Sorting Algorithms

   How the main sorts work, what they cost and how Java's own sort fits in.

   1. Why sorting matters25 min
   2. Bubble, selection and insertion sort30 min
   3. Merge sort32 min
   4. Counting inversions30 min
   5. Quick sort35 min
   6. Quickselect25 min
   7. Counting and radix sort25 min
   8. How Java sorts25 min
   9. Problems solved by sorting first25 min
   10. Practice: sorting25 min

5. 6.5Binary Trees

   1. Trees and tree words25 min
   2. Preorder, inorder and postorder25 min
   3. Traversals with a stack25 min
   4. Level order traversal25 min
   5. Height, diameter and balance25 min
   6. Paths in trees30 min
   7. Lowest common ancestor32 min
   8. Tree views, boundary and vertical order35 min
   9. Build and serialize trees35 min
   10. Practice: binary trees30 min

6. 6.6Binary Search Trees

   1. The BST rule25 min
   2. Insert into a BST28 min
   3. Delete from a BST32 min
   4. Validate a BST28 min
   5. Using sorted order30 min
   6. Floor, ceiling and LCA in a BST30 min
   7. Why balance matters32 min
   8. Build a balanced BST30 min
   9. TreeMap in problem solving35 min
   10. Practice: BSTs30 min

7. 6.7Heaps & Tries

   1. What a heap is25 min
   2. Build a heap yourself30 min
   3. Heap sort30 min
   4. PriorityQueue in Java25 min
   5. Top k problems32 min
   6. Two heaps: running median30 min
   7. Scheduling with heaps32 min
   8. Tries28 min
   9. Trie applications32 min
   10. Practice: heaps and tries30 min

8. 6.8Graphs: Basics & Traversal

   1. What a graph is25 min
   2. Storing graphs in Java28 min
   3. Breadth-first search32 min
   4. Depth-first search30 min
   5. Connected components28 min
   6. Grids as graphs30 min
   7. Cycle detection32 min
   8. Bipartite graphs30 min
   9. Practice: graph traversal35 min

9. 6.9Graph Algorithms

   1. Shortest path with BFS30 min
   2. Multi-source BFS30 min
   3. 0-1 BFS32 min
   4. Dijkstra algorithm35 min
   5. Topological sort32 min
   6. Disjoint set union34 min
   7. Minimum spanning trees35 min
   8. Graph algorithms practice40 min

10. 6.10Advanced Graph Algorithms

    1. Bellman-Ford30 min
    2. Floyd-Warshall30 min
    3. Shortest and longest paths in a DAG25 min
    4. Graphs hidden in problems30 min
    5. Strongly connected components30 min
    6. Bridges and articulation points30 min
    7. Euler paths and circuits30 min
    8. Maximum flow and matching (overview)30 min
    9. Practice: advanced graphs35 min

11. 6.11Greedy Algorithms & Intervals

    1. What greedy means25 min
    2. Activity selection30 min
    3. Merge and insert intervals30 min
    4. Meeting rooms30 min
    5. Jump game and gas station30 min
    6. Greedy with heaps30 min
    7. Fractional knapsack and the limits of greedy30 min
    8. Practice: greedy and intervals35 min

12. 6.12Dynamic Programming (1D)

    1. What dynamic programming is25 min
    2. Memoization25 min
    3. Tabulation25 min
    4. The DP recipe30 min
    5. Climbing stairs and house robber30 min
    6. Coin change30 min
    7. Decode ways and word break30 min
    8. Longest increasing subsequence30 min
    9. Saving space in DP25 min
    10. Best Time to Buy and Sell Stock30 min
    11. 1D Dynamic Programming Practice35 min

13. 6.13Dynamic Programming: 2D & Common Families

    1. Grid paths30 min
    2. 0/1 knapsack35 min
    3. The subset sum family35 min
    4. Unbounded knapsack35 min
    5. Longest common subsequence35 min
    6. Edit distance35 min
    7. Palindrome DP35 min
    8. Solving a new DP problem35 min
    9. Practice: 2D DP35 min

14. 6.14Advanced Dynamic Programming

    1. Interval dynamic programming35 min
    2. Bitmask dynamic programming35 min
    3. Tree dynamic programming35 min
    4. Digit dynamic programming35 min
    5. Game theory dynamic programming35 min
    6. Classic hard dynamic programming35 min
    7. DP optimisations: prefix sums and monotonic queues35 min
    8. Matrix exponentiation: linear recurrences in logarithmic time35 min
    9. Comprehensive advanced DP practice40 min

15. 6.15String Algorithms

    1. Searching text25 min
    2. Rolling hash and Rabin-Karp35 min
    3. The KMP algorithm35 min
    4. The Z-algorithm35 min
    5. Palindrome algorithms35 min
    6. Practice: string algorithms35 min

16. 6.16Advanced Data Structures

    1. The range query problem25 min
    2. Segment trees35 min
    3. Lazy propagation35 min
    4. Fenwick trees35 min
    5. Sparse table: O(1) static range minimum queries28 min
    6. Designing complex composite data structures30 min
    7. Advanced data structures in practice32 min

17. 6.17DSA Problem Sets

    1. Topic set: lists, stacks and queues28 min
    2. Topic set: hashing and sorting28 min
    3. Topic set: trees, heaps and tries30 min
    4. Topic set: graphs32 min
    5. Topic set: greedy and DP32 min
    6. Mixed sets: choose the structure35 min
    7. DSA revision sheet30 min
    8. DSA checkpoint35 min