The Java Algorithms online test assesses candidates' algorithmic-thinking skills and their ability to implement algorithms using Java.
It's an ideal test for pre-employment screening. A good developer will be able to design and implement algorithms that are both correct and efficient. Computational complexity is important not only when scaling applications but when creating responsive, maintainable, and efficient code.
This online test requires candidates to analyze or design an algorithm using Java as the programming language.
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Sample Free Questions
Binary Search Tree
15min
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Easy
Easy
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CODE
Java
Algorithmic thinking
Data structures
Public
Java
The Java programming language is a simple, modern, general-purpose, object-oriented programming language. Having a basic familiarity with the programming language used on the job is a prerequisite for quickly getting up to speed.
Algorithmic thinking
When designing and/or analyzing an algorithm or data structure, it is important to consider the performance and structure of an implementation. Algorithmic thinking is one of the key traits of a good programmer, especially one working on complex or performance-critical code.
Data structures
Choosing the right data structure to solve a problem can have huge implications on the performance of an application. Knowing when to use a specific data structure is one of the most important skills for a programmer.
Public
Public questions (free account) are common interview questions. They are great for practicing, or if you want to filter candidates using the classic problems.
Binary search tree (BST) is a binary tree where the value of each node is larger or equal to the values in all the nodes in that node's left subtree and is smaller than the values in all the nodes in that node's right subtree.
Write a function that, efficiently with respect to time used, checks if a given binary search tree contains a given value.
For example, for the following tree:
- n1 (Value: 1, Left: null, Right: null)
- n2 (Value: 2, Left: n1, Right: n3)
- n3 (Value: 3, Left: null, Right: null)
Call to contains(n2, 3) should return true since a tree with root at n2 contains number 3.
Two Sum
30min
-
Easy
Easy
-
CODE
Java
Algorithmic thinking
Searching
Public
Java
The Java programming language is a simple, modern, general-purpose, object-oriented programming language. Having a basic familiarity with the programming language used on the job is a prerequisite for quickly getting up to speed.
Algorithmic thinking
When designing and/or analyzing an algorithm or data structure, it is important to consider the performance and structure of an implementation. Algorithmic thinking is one of the key traits of a good programmer, especially one working on complex or performance-critical code.
Searching
Every programmer should be familiar with data-searching methods, as they are very common in data-analysis processes.
Public
Public questions (free account) are common interview questions. They are great for practicing, or if you want to filter candidates using the classic problems.
Write a function that, when passed a list and a target sum, returns, efficiently with respect to time used, two distinct zero-based indices of any two of the numbers, whose sum is equal to the target sum. If there are no two numbers, the function should return null.
For example, findTwoSum(new int[] { 3, 1, 5, 7, 5, 9 }, 10) should return a single dimensional array with two elements and contain any of the following pairs of indices:
- 0 and 3 (or 3 and 0) as 3 + 7 = 10
- 1 and 5 (or 5 and 1) as 1 + 9 = 10
- 2 and 4 (or 4 and 2) as 5 + 5 = 10
Sorted Search
20min
-
Hard
Hard
-
CODE
Java
Algorithmic thinking
Searching
Public
Java
The Java programming language is a simple, modern, general-purpose, object-oriented programming language. Having a basic familiarity with the programming language used on the job is a prerequisite for quickly getting up to speed.
Algorithmic thinking
When designing and/or analyzing an algorithm or data structure, it is important to consider the performance and structure of an implementation. Algorithmic thinking is one of the key traits of a good programmer, especially one working on complex or performance-critical code.
Searching
Every programmer should be familiar with data-searching methods, as they are very common in data-analysis processes.
Public
Public questions (free account) are common interview questions. They are great for practicing, or if you want to filter candidates using the classic problems.
Implement function countNumbers that accepts a sorted array of unique integers and, efficiently with respect to time used, counts the number of array elements that are less than the parameter lessThan.
For example, SortedSearch.countNumbers(new int[] { 1, 3, 5, 7 }, 4) should return 2 because there are two array elements less than 4.
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Utilities, Runner, Document Store, Needle, Log Parser, Driver Exam, Crop Ratio, Programmer Teacher, Chicken, Paragraph, Username, Chain Link, Hobbies, Read First Line, Node, Shipping, Racer, Snapshot, Date Transform, Segment, Internal Nodes, Moving Total, Entry, Unique Numbers, Remove Repetitions, Max Sum, Unique Name, Friend, Paper Strip, Stories, Train, Platformer, Weighted Average, Test Results, Product, Unloading Trucks, Shelf, Rare, Stack to List, Read Write Execute, Shining Star, Document Counter, Snow StormSkills
JavaJava
The Java programming language is a simple, modern, general-purpose, object-oriented programming language. Having a basic familiarity with the programming language used on the job is a prerequisite for quickly getting up to speed.
OOP
Object-oriented programming is a paradigm based on encapsulating logic and data into objects, which may then contain fields and procedures. Many of the most widely used programming languages are based on OOP, making it a very important concept in modern programming.
Bug fixing
Everyone makes mistakes. A good programmer should be able to find and fix a bug in their or someone else's code.
Memory management
Memory management allows programs to request memory dynamically from the operating system, and free it for reuse when no longer needed. Many modern programming languages automate this process; however, it should still be an important consideration when implementing an application.
Language
A programmer should use a language as a tool, always taking advantage of language-specific data types and built-in functions.
Stream
A stream is a sequence of data elements made available over time. It is particularly useful for tasks that may benefit from being asynchronous, including tasks such as I/O processing or reading from a file, and as such is important for developers to understand.
Strings
The string data structure is used to represent text. It is one of the most commonly used data structures. Therefore, every programmer should be skilled at string manipulation.
Serialization
Familiarity with data serialization to and from formats such as XML and JSON is important as it is commonly used for interprocess communication
Exceptions
Exceptions exist in most modern programming languages, making it important for a programmer to understand them and know how to handle them.
Data structures
Choosing the right data structure to solve a problem can have huge implications on the performance of an application. Knowing when to use a specific data structure is one of the most important skills for a programmer.
Arrays
An array is a container of a fixed number of objects of a similar type. It is a fundamental component of most programming languages.
Iteration
Iteration is the act of repeating a process, or cycling through a collection. Iteration is one of the fundamental flow control tools available to developers.
Arithmetic
Arithmetic is a fundamental branch of mathematics. An understanding of arithmetic concepts, and their application, is important for every candidate.
Multithreading
Multi-threading allows a process to make more efficient use of modern hardware by allowing code to execute asynchronously. It can drastically improve the performance of any app; however, it can be tricky to get right, making this an important topic for any programmer.
Algorithmic thinking
When designing and/or analyzing an algorithm or data structure, it is important to consider the performance and structure of an implementation. Algorithmic thinking is one of the key traits of a good programmer, especially one working on complex or performance-critical code.
Searching
Every programmer should be familiar with data-searching methods, as they are very common in data-analysis processes.
Graphs
Many real-life situations are best modeled by graphs. Therefore, an in-depth knowledge of graph data structures is important for a good programmer.
Dynamic programming
Dynamic programming methods for code optimization can be very useful to a programmer who understands them.
Refactoring
The process of restructuring existing computer code without changing its external behavior. It is essential for keeping code readable and maintainable.
Sorting
Every programmer should be familiar with data-sorting methods, as sorting is very common in data-analysis processes.
Test case design
Being able to create a set of test cases that ensure adequate test coverage is a key skill for creating a successful test. It is desirable for the test suite also to be optimal, i.e. to minimize test execution effort and time without affecting the test coverage.
TDD
Test-driven development (TDD) is a software development process that relies on the repetition of a very short development cycle: requirements are turned into very specific test cases, based on which the software is improved only in order to pass the new tests. TDD is an essential skill for modern programmers.
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