Java Code Examples

Class-based, object-oriented enterprise language designed for JVM portability, robust standard libraries, and multithreading. Learn by testing verified runnable code samples, algorithmic walkthroughs, and step-by-step logic explanations.

Trees & BFS

O(N)

Java Binary Tree Level Order Traversal (BFS)

Traverse a binary tree level by level using Breadth-First Search (BFS) with an ArrayDeque queue in Java.

Java Invert / Mirror Binary Tree

Invert a binary tree by recursively swapping left and right child pointers.

Runnable Code

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Data Structures & Algorithms

O(N) single-pass lookup

Java Two Sum Problem (Optimized One-Pass HashMap)

Find two indices in an array of integers that add up to a specific target number using a single-pass HashMap in O(n) time.

Java Program to Reverse a String (StringBuilder & Two Pointers)

Reverse strings in Java efficiently using StringBuilder and in-place char array two-pointer swapping.

Runnable Code

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Java Code Examples

Java Binary Tree Level Order Traversal (BFS)

Java Invert / Mirror Binary Tree

Java Two Sum Problem (Optimized One-Pass HashMap)

Java Program to Reverse a String (StringBuilder & Two Pointers)

Platform & Tools

Account

Company & Help

Legal & Policies

Java Code Examples

Java Binary Tree Level Order Traversal (BFS)

Java Invert / Mirror Binary Tree

Java Two Sum Problem (Optimized One-Pass HashMap)

Java Program to Reverse a String (StringBuilder & Two Pointers)