Java Recursion Practice

A compact Java playground to practice classic recursion problems and experiment with a simple Red-Black Tree implementation.

What’s inside

• Practice problems implemented in src/RecursionSolver.java
• A small demo runner in src/MainApplication.java (now only demonstrates Red-Black Tree)
• A minimal Red-Black Tree node implementation in src/redBlackTreeOperations/
• JUnit 5 tests for tree behavior in test/RBNodeTest.java

Tasks covered

• Factorial
• Fibonacci (N-th member)
• Sum of digits
• Array sum
• Array max
• Count occurrences in array
• GCD (Greatest Common Divisor)
• Palindrome check
• Power (exponentiation)
• Red-Black Tree operations (toy implementation: insert, delete, rotate, traversal, color-fix)

Project structure

java-recursion-practice/
  lib/                         # JUnit 5 & dependencies (JARs)
  src/
    MainApplication.java       # Quick manual demo
    RecursionSolver.java       # Recursion exercises
    redBlackTreeOperations/
      Color.java
      RBNode.java
      RotateCondition.java
      TraversalType.java
  test/ # JUnit 5 tests
    RBNodeTest.java
    RecursionSolverTest.java

Requirements

• Java 17+ (recommended)
• Gradle Wrapper included (./gradlew, gradlew.bat)
• Any IDE with Gradle & JUnit 5 support

Build & run with Gradle

Using the Gradle Wrapper from the project root:

# Windows PowerShell
./gradlew.bat clean build
./gradlew.bat run

This runs MainApplication and prints Red-Black Tree traversals. Recursion tasks are validated via unit tests.

Run tests

With Gradle (JUnit 5):

# Windows PowerShell
./gradlew.bat test

Your IDE can also run RBNodeTest directly using the Gradle test runner.

Notes on the Red-Black Tree

The RBNode here is intentionally minimal and educational. It exposes basic operations and prints simple traversals. It is not a full production-grade Red-Black Tree, but it’s useful for practicing invariants, rotations, and color adjustments.

License

This project is provided for educational purposes. Use it freely.