Coding practice problems on LeetCode and LaiCode

A collection of algorithm and data structure solutions implemented in Java 11, built with Maven.

Project Structure

coding-practice/
├── coollime/                 # Maven project
│   ├── src/
│   │   ├── main/java/        # Solution implementations
│   │   └── test/java/        # Unit tests
│   └── pom.xml               # Maven configuration
├── docs/                     # Documentation for each algorithm
└── scripts/                  # Git hooks setup scripts

Getting Started

Prerequisites

• Java 11 or higher
• Maven 3.6+

Setup

1. Clone the repository
2. Install git hooks (optional but recommended):

   ./scripts/setup-git-hooks.sh

Build & Test

# Build the project
cd coollime && mvn clean install

# Run tests
mvn test

# Format code
mvn spotless:apply

# Check code quality
mvn verify

Code Quality Tools

This project uses the following Maven plugins for code quality:

• Spotless - Code formatting (Google Java Format, AOSP style)

• Checkstyle - Code style enforcement (Google checks)

• SpotBugs - Static analysis for bug detection

• Completed:

  • Sorting Algorithms
  • Binary Search
  • Recursion
  • Queue & Stack
  • Linked List
  • Binary Tree

Table of Contents

1. Sorting Algorithms

   1. Selection Sort
   2. Merge Sort
   3. Quick Sort
   4. Move 0's to the End I
   5. Rainbow Sort

2. Binary Search

   1. Classical Binary Search
   2. Search in Sorted Matrix I
   3. Closest in Sorted Array
   4. First Occurrence
   5. Last Occurrence
   6. K Closest in Sorted Array
   7. Search in Unknown Sized Sorted Array
   8. Find Minimum in Rotated Sorted Array

3. Recursion

   1. Fibonacci Number
   2. A to the Power of B

4. Queue & Stack

   1. Sort with 3 Stacks
   2. Queue by Two Stacks
   3. Stack with min()
   4. Sort with 2 Stacks

5. Linked List

   1. Reverse Linked List
   2. Middle Node of Linked List
   3. Check if Linked List Has a Cycle
   4. Insert in Sorted Linked List
   5. Merge Two Sorted Linked Lists
   6. Reorder Linked List
   7. Partition Linked List
   8. Add Two Numbers
   9. Merge Sort Linked List
   10. Check if Linked List is Palindrome
   11. Cycle Node in Linked List

6. Binary Tree

   1. In-order Traversal of Binary Tree
   2. Pre-order Traversal of Binary Tree
   3. Post-order Traversal of Binary Tree
   4. Check if Binary Tree is Balanced
   5. Symmetric Binary Tree
   6. Tweaked Identical Binary Trees
   7. Is Binary Search Tree or Not
   8. Get Keys in Binary Search Tree in Given Range
   9. Binary Tree Path Sum to Target I
   10. Search in Binary Search Tree
   11. Insert in Binary Search Tree

7. Heap & Graph Search Algorithms I (BFS)

   1. K Smallest in Unsorted Array
   2. Get Keys in Binary Tree Layer by Layer
   3. Bipartite
   4. Check if Binary Tree is Completed
   5. Kth Smallest Number in Sorted Matrix
   6. Number of Islands
   7. Walls and Gates

8. DFS

   1. All Subsets I
   2. All Valid Permutations of Parentheses I
   3. Combinations of Coins
   4. All Permutations I

9. HashTable

   1. Top K Frequent Words
   2. Missing Number I
   3. Common Numbers of Two Sorted Arrays

10. String I

    1. Remove Certain Characters
    2. Remove Spaces
    3. Remove Adjacent Repeated Characters I
    4. Remove Adjacent Repeated Characters IV
    5. Determine if One String is Another's Substring

11. String II

    1. Reverse String
    2. Reverse Words in a Sentence I
    3. Right Shift by N Characters
    4. String Replace
    5. ReOrder Array
    6. All Permutations II
    7. Decompress String II
    8. Longest Substring without Repeating Characters
    9. All Anagrams

12. Bit Representation & Operation

    1. Power of Two
    2. Number of Different Bits
    3. All Unique Characters II
    4. Hexadecimal Representation

13. DFS II

    1. All Subsets II
    2. All Valid Permutations of Parentheses II
    3. All Subsets Size of K

14. Dynamic Programming I

    1. Longest Ascending SubArray
    2. Max Product of Cutting Rope
    3. Array Hopper I

15. Dynamic Programming II

    1. Array Hopper II
    2. Largest SubArray Sum
    3. Dictionary Word I
    4. Edit Distance
    5. Largest Square of 1's

16. Dynamic Programming III

    1. Largest SubArray Sum
    2. Longest Consecutive 1's
    3. Longest Cross of 1's
    4. Largest X of 1's
    5. Largest SubMatrix Sum

17. Probability, Sampling & Randomization

    1. Perfect Shuffle
    2. Reservoir Sampling
    3. Random7 Using Random5
    4. Random1000 Using Random5
    5. Median Tracker
    6. 95 Percentile

18. Recursion II

    1. N Queens
    2. Spiral Order Traverse I
    3. Spiral Order Traverse II
    4. Lowest Common Ancestor I
    5. Lowest Common Ancestor II
    6. Maximum Path Sum Binary Tree III
    7. Maximum Path Sum Binary Tree II
    8. Binary Tree Path Sum to Target III

19. Cross Training I

    1. Array Deduplication I
    2. Array Deduplication II
    3. Array Deduplication III
    4. Array Deduplication IV
    5. Move 0's to the End II
    6. Largest and Smallest
    7. Largest and Second Largest
    8. Get Keys in Binary Tree Layer by Layer Zig-Zag Order
    9. Rotate Matrix
    10. Two Sum
    11. Two Sum All Pair I
    12. Two Sum All Pair II
    13. Three Sum

20. Cross Training II

    1. Deep Copy Linked List with Random Pointer
    2. Deep Copy Undirected Graph
    3. Merge K Sorted Arrays
    4. Merge K Sorted Lists
    5. Closest Number in Binary Search Tree
    6. Largest Number Smaller in Binary Search Tree
    7. Delete in Binary Search Tree

21. Cross Training III

22. Cross Training IV

    1. Kth Smallest in Two Sorted Arrays
    2. Maximum Values of Size K Sliding Windows
    3. Implement LRU Cache
    4. First Non-Repeating Character in Stream
    5. Majority Number I

23. Cross Training V

24. Cross Training VI

    1. Longest Ascending Subsequence
    2. Longest Common Substring

25. Free Practice

    1. Palindrome Permutation
    2. Palindrome Permutation II
    3. Plus One
    4. Clone Graph