🌳 LeetCode Trees Series (Java Solutions)

This repository contains Java solutions for tree-based problems from LeetCode. It is designed for coding interview preparation and to help developers strengthen their Tree and Binary Search Tree (BST) knowledge.

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📌 Topics Covered

• Binary Tree Basics

  • Traversals (Preorder, Inorder, Postorder, Level-order)
  • Maximum Depth / Minimum Depth
  • Diameter of Binary Tree
  • Path Sum Problems

• Binary Search Trees (BST)

  • Insertion, Deletion, Search
  • Validate BST
  • Lowest Common Ancestor
  • Convert Sorted Array to BST

• Advanced Tree Problems

  • Serialize & Deserialize Binary Tree
  • Construct Tree from Traversals
  • Flatten Binary Tree to Linked List
  • Binary Tree Cameras
  • Recover BST

• Special Trees

  • N-ary Trees
  • Trie (Prefix Tree)
  • Segment Tree
  • Fenwick Tree (Binary Indexed Tree)

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🛠️ How to Run

1. Clone the repo

   git clone https://github.com/<your-username>/LeetCode_Trees_Series.git
   cd LeetCode_Trees_Series

2. Compile and run Java files

   javac Solution.java
   java Solution

3. Each problem is stored in a separate folder with the following format:

   <problem_number>_<problem_name>/
       ├── Solution.java
       ├── README.md  (explanation + approach)
   

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📂 Repository Structure

LeetCode_Trees_Series/
│
├── Binary_Tree/
│   ├── 0104_Maximum_Depth_of_Binary_Tree/
│   │   ├── Solution.java
│   │   └── README.md
│   ├── 0110_Balanced_Binary_Tree/
│   │   ├── Solution.java
│   │   └── README.md
│   └── ...
│
├── Binary_Search_Tree/
│   ├── 0098_Validate_BST/
│   │   ├── Solution.java
│   │   └── README.md
│   ├── 0700_Search_in_BST/
│   │   ├── Solution.java
│   │   └── README.md
│   └── ...
│
└── Advanced_Trees/
    ├── 0297_Serialize_and_Deserialize_BT/
    │   ├── Solution.java
    │   └── README.md
    └── ...

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🧠 Problem Format

Each problem folder contains:

• README.md

  • Problem Link
  • Intuition
  • Approach
  • Complexity Analysis (Time & Space)

• Solution.java

  /**
   * Problem: 104. Maximum Depth of Binary Tree
   * Link: https://leetcode.com/problems/maximum-depth-of-binary-tree/
   *
   * Time Complexity: O(n)
   * Space Complexity: O(h) where h is tree height
   */
  class Solution {
      public int maxDepth(TreeNode root) {
          if (root == null) return 0;
          return 1 + Math.max(maxDepth(root.left), maxDepth(root.right));
      }
  }

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🎯 Goals of this Repo

• ✅ Build a complete set of Java tree solutions for LeetCode.
• ✅ Provide clear explanations + clean code.
• ✅ Cover both easy, medium, and hard tree problems.
• ✅ Help students & professionals crack FAANG / top company interviews.

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🤝 Contributing

• Fork the repo & add your solution.
• Make sure code is properly formatted and commented.
• Submit a PR 🚀

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⭐ Support

If you find this repository helpful, please star ⭐ it and share with friends preparing for DSA in Java!

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