Java Projects — Data Structures & Algorithms

A portfolio of Java programming projects completed as part of COMS W3134 (Data Structures in Java) at Columbia University. Each project demonstrates core CS concepts including algorithm design, object-oriented programming, and data structure implementation from scratch.

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Projects

01 · Newton's Method Square Root

Directory: square-root/src/SquareRoot.java

Implements the Babylonian (Newton's method) algorithm to compute square roots iteratively to a configurable precision (epsilon). Handles edge cases including negative numbers, zero, NaN, and infinity.

• Concepts: Iterative numerical methods, error tolerance, command-line argument parsing

• • Key method: sqrt(double num, double epsilon)

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  02 · Recursive Algorithms

  Directory: recursive-algorithms/src/Recursion.java

  A suite of six recursive algorithms implemented without any iterative constructs, demonstrating mastery of base cases, recursive decomposition, and helper-method patterns.

  • Concepts: Recursion, tail recursion, string manipulation, array traversal

  • • Methods: recursiveMultiplication, reverse, max, isPalindrome, isMember, separateIdentical

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    03 · Custom List Implementations

    Directory: custom-list/src/

    From-scratch implementations of ArrayList and LinkedList conforming to a custom MyList interface, plus a MadLibGenerator application that uses the lists to parse and fill in Mad Libs templates.

    • Concepts: Dynamic arrays, doubly-linked lists, generics, iterator pattern

    • • Files: MyArrayList.java, MyLinkedList.java, MyList.java, MadLibGenerator.java

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      04 · Stack-Based Infix Expression Evaluator

      Directory: expression-evaluator/src/

      Implements a MyStack interface backed by a linked list, then uses two stacks (operands + operators) to evaluate arithmetic infix expressions with full operator precedence and parenthesis support.

      • Concepts: Stack ADT, expression parsing, operator precedence, OOP design

      • • Files: MyStack.java, IntCalculator.java, MyArrayList.java

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        05 · JUnit Test Suite

        Directory: unit-tests/lib/

        Comprehensive JUnit 5 test suite validating the custom data structure implementations from previous assignments. Covers boundary conditions, exception handling, and correctness of all public APIs.

        • Concepts: Unit testing, test-driven development, JUnit 5, boundary analysis

        • • Tools: JUnit Jupiter 5.10, Hamcrest

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          06 · Binary Search Tree & Red-Black Tree Map

          Directory: tree-maps/src/

          Full implementations of BSTreeMap and RBTreeMap conforming to a MyMap interface. The Red-Black Tree maintains self-balancing invariants through rotations and recoloring, guaranteeing O(log n) operations.

          • Concepts: BST, self-balancing trees, tree rotations, red-black invariants, map ADT

          • • Files: BSTreeMap.java, RBTreeMap.java, MyMap.java, Node.java, RBNode.java

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            07 · Hash Map with Separate Chaining

            Directory: hash-map/src/

            Custom MyHashMap implementation using an array of linked lists (separate chaining) for collision resolution, with dynamic resizing and a polynomial rolling hash function.

            • Concepts: Hash tables, separate chaining, load factor, dynamic resizing, hash functions

            • • Files: MyHashMap.java, MyMap.java, Entry.java

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              08 · Inversion Counter

              Directory: inversion-counter/src/

              Counts the number of inversions in an integer array using a modified merge sort algorithm in O(n log n) time, compared against a brute-force O(n²) baseline.

              • Concepts: Divide and conquer, merge sort, algorithm complexity analysis

              • • Files: InversionCounter.java

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                Tech Stack

                Tool	Version
                Java	17+
                JUnit	Jupiter 5.10
                IDE	IntelliJ IDEA

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                Course

                COMS W3134 — Data Structures in Java Columbia University