This HTML/CSS, JavaScript, Java Algorithms, and SQL Online Test Separates Good From Bad Hires

Every user on your website has an image avatar that is displayed when they post a comment. You want to style these images differently from other images on your site. Add a CSS class named avatar that fulfils the following requirements:

1. The avatar's border is rounded, so that it appears as a circle.
2. The avatar's width and height are both 150px.
3. The avatar has a solid border, has a width of 2px, and be colored gray.

For example, the avatar in the template should look like:

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.

Implement the ensure function so that it throws an error if called without arguments or the argument is undefined. Otherwise it should return the given value.

Given the following data definition, write a query that returns the number of students whose first name is John.

TABLE students
   id INTEGER PRIMARY KEY,
   firstName VARCHAR(30) NOT NULL,
   lastName VARCHAR(30) NOT NULL

A company is designing the class hierarchy for various cache implementations:

public class Cache {}

public class DiskCache extends Cache {}

public class MemoryCache extends Cache {}

public class OptimizedDiskCache extends DiskCache {}

Select all the answers that will result in a runtime exception.

A table containing the students enrolled in a yearly course has incorrect data in records with ids between 20 and 100 (inclusive).

TABLE enrollments
  id INTEGER NOT NULL PRIMARY KEY
  year INTEGER NOT NULL
  studentId INTEGER NOT NULL

Write a query that updates the field 'year' of every faulty record to 2015.

A Mathematics tutoring web application for kids has a button that highlights all even numbers (in span), using 'yellow' as the background color. Clicking the button again removes the background. All further clicks add or remove the 'yellow' background alternately.

Currently, the button doesn't work as expected. For the given HTML markup and JavaScript function, select all options that will identify and fix the bugs in the JavaScript function:

<div id='numbers'>
 <span>1</span><span>2</span><span>3</span><span>4</span><span>5</span>
 <button id='btn' onclick='toggleEvenColor()'>Toggle even number highlighting</button>
</div>

1: function toggleEvenColor() {
2:   let spanElements = document.querySelectorAll('#numbers span');
3:   spanElements.forEach(function() {
4:     item.style.backgroundColor = 'transparent';
5:   });
6: }

Information about pets is kept in two separate tables:

TABLE dogs
  id INTEGER NOT NULL PRIMARY KEY,
  name VARCHAR(50) NOT NULL

TABLE cats
  id INTEGER NOT NULL PRIMARY KEY,
  name VARCHAR(50) NOT NULL

Write a query that select all distinct pet names.

See the example case for more details.

A new social network site has the following data tables:

Select data that will be returned by the following SQL query:

SELECT users.name, COUNT(*) as count FROM users
LEFT JOIN friends
ON users.id = friends.user1 OR users.id = friends.user2
WHERE users.sex = 'f'
GROUP BY users.id, users.name;

Implement the removeProperty function which takes an object and property name, and does the following:

If the object obj has a property prop, the function removes the property from the object and returns true; in all other cases it returns false.

Update the website's HTML, without using JavaScript or CSS, to make use of semantic elements so that:

• The classless outer div element is replaced with a more appropriate element.
• The divs with the image and caption classes are replaced with self-contained content elements.
• The divs with the lorem-ipsum and description classes are replaced with elements, so that by default only the contents of the description element are shown. When the contents of the description element are clicked, the visibility of the rest of the lorem-ipsum element is toggled.

App usage data are kept in the following table:

TABLE sessions
  id INTEGER PRIMARY KEY,
  userId INTEGER NOT NULL,
  duration DECIMAL NOT NULL

Write a query that selects userId and average session duration for each user who has more than one session.

See the example case for more details.

You've been sent a snippet from a spreadsheet, and have been asked to re-create it for display on the company's internal website.

Re-create the following spreadsheet using HTML, in a table appropriately captioned "Purchase Orders".

Write CSS so that the link <a href="http://www.testdome.com">Check documentation</a> looks like the one in the image below, and the cursor looks like a question mark when hovering over the link:

Each item in a web shop belongs to a seller. To ensure service quality, each seller has a rating.

The data are kept in the following two tables:

TABLE sellers
  id INTEGER PRIMARY KEY,
  name VARCHAR(30) NOT NULL,
  rating INTEGER NOT NULL

TABLE items
  id INTEGER PRIMARY KEY,
  name VARCHAR(30) NOT NULL,
  sellerId INTEGER
  FOREIGN KEY (sellerId) REFERENCES sellers(id)

Write a query that selects the item name and the name of its seller for each item that belongs to a seller with a rating greater than 4. The query should return the name of the item as the first column and name of the seller as the second column.

See the example case for more details.

Refactor the AlertService and MapAlertDAO classes:

• Create a new package-private interface, named AlertDAO, that contains the same methods as MapAlertDAO.
• MapAlertDAO should implement the AlertDAO interface.
• AlertService should have a public constructor that accepts AlertDAO.
• The raiseAlert and getAlertTime methods should use the object passed through the constructor.

Write a function that converts user entered date formatted as M/D/YYYY to a format required by an API (YYYYMMDD). The parameter "userDate" and the return value are strings.

For example, it should convert user entered date "12/31/2014" to "20141231" suitable for the API.

Implement the IceCreamMachine's scoops method so that it returns all combinations of one ingredient and one topping. If there are no ingredients or toppings, the method should return an empty list.

For example,

IceCreamMachine machine = new IceCreamMachine(
    new String[]{"vanilla", "chocolate"},
    new String[]{"chocolate sauce"}
);
List<IceCream> scoops = machine.scoops();
for (IceCream iceCream : scoops) {
    System.out.println(iceCream.ingredient + ", " + iceCream.topping);
}

should print

vanilla, chocolate sauce
chocolate, chocolate sauce

An image gallery is a set of images with corresponding remove buttons. This is the HTML code for a gallery with two images:

<div class="image">
  <img src="https://bit.ly/3lmYVna" alt="First">
  <button class="remove">X</button>
</div>
<div class="image">
  <img src="https://bit.ly/3flyaMj" alt="Second">
  <button class="remove">X</button>
</div>

Implement the setup function that registers a click event handler and implements the following logic: When the button of class remove is clicked, its parent <div> element should be removed from the gallery.

For example, after the first image has been removed from the gallery above, it's HTML code should look like this:

<div class="image">
  <img src="https://bit.ly/3flyaMj" alt="Second">
  <button class="remove">X</button>
</div>

Fix the bugs in the following HTML code.

Implement the uniqueNames method. When passed two arrays of names, it will return an array containing the names that appear in either or both arrays. The returned array should have no duplicates.

For example, calling MergeNames.uniqueNames(new String[]{'Ava', 'Emma', 'Olivia'}, new String[]{'Olivia', 'Sophia', 'Emma'}) should return an array containing Ava, Emma, Olivia, and Sophia in any order.

Implement the function findRoots to find the roots of the quadratic equation: ax² + bx + c = 0. The function should return a Roots object containing roots in any order. If the equation has only one solution, the function should return that solution as both elements of the Roots. The equation will always have at least one solution.

The roots of the quadratic equation can be found with the following formula:

For example, findRoots(2, 10, 8) should return a Roots object where either x1 = -1, x2 = -4 or x1 = -4, x2 = -1 as the roots of the equation 2x² + 10x + 8 = 0 are -1 and -4.

Your company assigns each customer a membership ID, and you are implementing a check digit for those IDs.

The check digit should be calculated by adding up all digits in each membership ID. If the result of the sum is a number with more than a single digit, another iteration is required, and the digits of the result also should be added together. This process should repeat until a single-digit number is calculated.

For example, for the membership ID "55555" the sum of all digits is 25. Because this is not a single-digit number, 2 and 5 would be added, and the result, 7, would be the check digit.

A playlist is considered a repeating playlist if any of the songs contain a reference to a previous song in the playlist. Otherwise, the playlist will end with the last song which points to null.

Implement a function isRepeatingPlaylist that, efficiently with respect to time used, returns true if a playlist is repeating or false if it is not.

For example, the following code prints "true" as both songs point to each other.

Song first = new Song("Hello");
Song second = new Song("Eye of the tiger");
    
first.setNextSong(second);
second.setNextSong(first);
    
System.out.println(first.isRepeatingPlaylist());

A playlist is considered a repeating playlist if any of the songs contain a reference to a previous song in the playlist. Otherwise, the playlist will end with the last song which points to undefined.

Implement the method isRepeatingPlaylist that, efficiently with respect to time used, returns true if a playlist is repeating or false if it is not.

For example, the following code prints "true" as both songs point to each other.

let first = new Song("Hello");
let second = new Song("Eye of the tiger");

first.nextSong = second;
second.nextSong = first;

console.log(first.isRepeatingPlaylist());

Write the function newMessage, which receives the name of the topic as the parameter. Function should change the background color of the p tag to red where the data-topic-name is topicName. A topicName that doesn't have a matching data-topic-name should be ignored.

For example, if the HTML is:

<div>
  <p data-topic-name="discussion">General discussion</p>
  <p data-topic-name="bugs">Bugs</p>
  <p data-topic-name="animals">Animals</p>
</div>

After calling newMessage("discussion") the HTML should be:

<div>
  <p data-topic-name="discussion" style="background-color: red;">General discussion</p>
  <p data-topic-name="bugs">Bugs</p>
  <p data-topic-name="animals">Animals</p>
</div>

User interface contains two types of user input controls: TextInput, which accepts all characters and NumericInput, which accepts only digits.

Implement the class TextInput that contains:

• Public method void add(char c) - adds the given character to the current value
• Public method String getValue() - returns the current value

Implement the class NumericInput that:

• Inherits from TextInput
• Overrides the add method so that each non-numeric character is ignored

For example, the following code should output "10":

TextInput input = new NumericInput();
input.add('1');
input.add('a');
input.add('0');
System.out.println(input.getValue());

Using JUnit 4's Assert class, write tests for the Account class that cover the following cases:

• The deposit and withdraw methods will not accept negative numbers.
• Account cannot overstep its overdraft limit.
• The deposit and withdraw methods will deposit or withdraw the correct amount, respectively.
• The withdraw and deposit methods return the correct results.

public class Account {
    private double balance;
    private double overdraftLimit;
    
    public Account(double overdraftLimit) {
        this.balance = 0;
        this.overdraftLimit = overdraftLimit > 0 ? overdraftLimit : 0;
    }
    
    public boolean deposit(double amount) {
        if(amount >= 0) {
            this.balance += amount;
            return true;
        }
        return false;
    }
    
    public boolean withdraw(double amount) {
        if(this.balance - amount >= -this.overdraftLimit && amount >= 0) {
            this.balance -= amount;
            return true;
        }
        return false;
    }
    
    public double getBalance() {
        return balance;
    }
    
    public double getOverdraftLimit() {
        return overdraftLimit;
    }
}

Each of the test case methods should be in the AccountTest class and have the Test annotation.

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

Write a function that, when passed an array 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([ 3, 1, 5, 7, 5, 9 ], 10) should return an array containing 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

You're making the 'Buy' button for a movie ticket website, which has the class buy-button.

The buy-button class has the following CSS:

.buy-button {
  width: 100px;
  height: 100px;
  background: Orange;
  /* Make it a circle */
  border-radius: 50%;
  /* Center horizontally and vertically */
  display: flex;
  justify-content: center;
  align-items: center;
}

A 1 second animation named wiggle should be added to it so the button wiggles when the mouse hovers over it.

Rotating to 25 degrees clockwise (first 0.33 s), then to 25 degrees counterclockwise (second 0.33 s) and then returning to the original position.

It should look like this:

Which of the following would produce the desired animation?

With the new HTML5 features, modify the form so that:

• The formula input field suggests the following options when the user starts to type: "sin", "cos", "tan" and "cot".
• The iterations input field is a slider with possible values from 1 to 10.
• The precision input field is a number picker with possible values from 1 to 100, where 50 is the default value.

An HTML div element contains lists of endangered species grouped by continent and the species population status.

<div>
    <ul data-continent="North America">
        <li data-species="California condor">Critically Endangered</li>
        <li data-species="American bison">Near Threatened</li>
    </ul>
    <ul data-continent="Europe">
        <li data-species="Cave bear">Extinct</li>
    </ul>
</div>

Implement the function endangeredSpecies that returns how endangered a species is on a particular continent.

For example, endangeredSpecies('North America', 'American bison') should return 'Near Threatened'.

The following data definition defines an organization's employee hierarchy.

An employee is a manager if any other employee has their managerId set to this employee's id. That means John is a manager if at least one other employee has their managerId set to John's id.

TABLE employees
  id INTEGER NOT NULL PRIMARY KEY
  managerId INTEGER
  name VARCHAR(30) NOT NULL
  FOREIGN KEY (managerId) REFERENCES employees(id)

Write a query that selects only the names of employees who are not managers.

See the example case for more details.

As part of a data processing pipeline, complete the implementation of the pipeline function:

• The pipeline function should accept a variable number of functions, and it should return a new function that accepts one parameter arg.
• The returned function should call the first function in the pipeline with the parameter arg, and call the second function with the result of the first function.
• The returned function should continue calling each function in the pipeline in order, following the same pattern, and return the value from the last function.

For example, pipeline(x => x * 3, x => x + 1, x => x / 2) then calling the returned function with 3 should return 5.0.

The following two tables are used to define users and their respective roles:

TABLE users
  id INTEGER NOT NULL PRIMARY KEY,
  userName VARCHAR(50) NOT NULL

TABLE roles
  id INTEGER NOT NULL PRIMARY KEY,
  role VARCHAR(20) NOT NULL

The users_roles table should contain the mapping between each user and their roles. Each user can have many roles, and each role can have many users.

Modify the provided SQL create table statement so that:

• Only users from the users table can exist within users_roles.
• Only roles from the roles table can exist within users_roles.
• A user can only have a specific role once.

See the example case for more details.

Fix the bugs in the registerHandlers function. An alert should display anchor's zero-based index within a document instead of following the link.

For example, in the document below, the alert should display "2" when Google anchor is clicked since it is the third anchor element in the document and its zero-based index is 2.

<body>
  In my life, I used the following web search engines:<br/>
  <a href="//www.yahoo.com">Yahoo!</a><br/>
  <a href="//www.altavista.com">AltaVista</a><br/>
  <a href="//www.google.com">Google</a><br/>
</body>

Implement methods in the DecoratorStream class:

• write method should write the prefix into the underlying stream member only on the first write invocation. It should always write the bytes it receives to the underlying stream.
• The prefix should be written in UTF-8 encoding.

For example, if the DecoratorStream is instantiated with "First line: " as the prefix parameter and write method is called with UTF-8 byte representation of "Hello, world!", it should write "First line: Hello, world!" into the underlying stream.

Function appendChildren should add a new child div to each existing div. New divs should be decorated by calling decorateDiv.

For example, after appendChildren is executed, the following divs:

<div id="a">
  <div id="b">
  </div>
</div>

should take the following form (assuming decorateDiv does nothing):

<div id="a">
  <div id="b">
    <div></div>
  </div>
  <div></div>
</div>

The code below should do the job, but for some reason it goes into an infinite loop. Fix the bugs.

Using CSS only (without adding additional HTML attributes), style articles so that they occupy the whole browser window and have the following properties:

Implement a function folderNames, which accepts a string containing an XML file that specifies folder structure and returns all folder names that start with startingLetter. The XML format is given in the example below.

For example, for the letter 'u' and an XML file:

<?xml version="1.0" encoding="UTF-8"?>
<folder name="c">
    <folder name="program files">
        <folder name="uninstall information" />
    </folder>
    <folder name="users" />
</folder>

the function should return a collection with items "uninstall information" and "users" (in any order).

A website needs a list where users can rank their favorite foods. Write the setup function, which should register click handlers on all Up! and Down! buttons. The Up! button should move the list item one place up in the list, while Down! button should move the list item one place down in the list.

For example, consider this code:

document.body.innerHTML = `<ol>
  <li><button>Up!</button>Taco<button>Down!</button></li>
  <li><button>Up!</button>Pizza<button>Down!</button></li>
  <li><button>Up!</button>Eggs<button>Down!</button></li>
</ol>`;

setup();

If the button Up! button in Pizza list item is clicked, Pizza should be the first item in the list, while Taco should be the second item.

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.

A TrainComposition is built by attaching and detaching wagons from the left and the right sides, efficiently with respect to time used.

For example, if we start by attaching wagon 7 from the left followed by attaching wagon 13, again from the left, we get a composition of two wagons (13 and 7 from left to right). Now the first wagon that can be detached from the right is 7 and the first that can be detached from the left is 13.

Implement a TrainComposition that models this problem.

The following HTML represents a family tree:

<James>
  <Dave></Dave>
  <Mike></Mike>
  <Sarah></Sarah>
</James>

Implement the closestRelative function so that when a parent HTML element is passed, the function returns the parent's closest relative whose name matches the relativeName, and obeys the following rules:

• The parent parameter is the HTML element of which the closest relative will be a descendant.
• Each member of the family, including children, may also be a parent to one or more children.
• Children are more closely related to the parent than grandchildren.
• If several children in the same generation have the same name, then the first child in the tree is considered the closer relative.
• If no matching relative is found the function should return null.

For example, the below code should print 'MIKE' for the given family tree:

let parent = document.getElementsByTagName('James')[0];
let relative = closestRelative(parent, 'Mike');
console.log(relative && relative.tagName); // prints MIKE

Implement the showCustomers function so that it renders customers as list items. The first argument to the function, customers, is an array of objects with the name and email properties. The second argument to the function, targetList, is an unordered HTML list to which each customer should be added as a separate list item.

The name and email properties should be added as two paragraphs inside the list item. At first, the email paragraph element should not be present in the DOM. The email paragraph element should be added to the DOM after the name is clicked, and it should be removed from the DOM when the name is clicked again.

For example, the following code:

document.body.innerHTML = `
<div>
  <ul id="customers">
  </ul>
</div>
`;
let customers = [{name: "John", email: "john@example.com"},
                 {name: "Mary", email: "mary@example.com"}];
showCustomers(customers, document.getElementById("customers"));

let customerParagraph = document.querySelectorAll("li > p")[0];
if(customerParagraph) {
  customerParagraph.click();
}
console.log(document.body.innerHTML);

Should render:

<div>
  <ul id="customers">
    <li>
      <p>John</p>
      <p>john@example.com</p>
    </li>
    <li>
      <p>Mary</p>
    </li>
  </ul>
</div>

An insurance company maintains records of sales made by its employees. Each employee is assigned to a state. States are grouped under regions. The following tables contain the data:

TABLE regions
  id INTEGER PRIMARY KEY
  name VARCHAR(50) NOT NULL

TABLE states
  id INTEGER PRIMARY KEY
  name VARCHAR(50) NOT NULL
  regionId INTEGER NOT NULL
  FOREIGN KEY (regionId) REFERENCES regions(id)

TABLE employees
  id INTEGER PRIMARY KEY
  name VARCHAR(50) NOT NULL
  stateId INTEGER NOT NULL
  FOREIGN KEY (stateId) REFERENCES states(id)

TABLE sales
  id INTEGER PRIMARY KEY
  amount INTEGER NOT NULL
  employeeId INTEGER NOT NULL
  FOREIGN KEY (employeeId) REFERENCES employees(id)  

Management requires a comparative region sales analysis report.

Write a query that returns:

• The region name.
• Average sales per employee for the region (Average sales = Total sales made for the region / Number of employees in the region).
• The difference between the average sales of the region with the highest average sales, and the average sales per employee for the region (average sales to be calculated as explained above).

Employees can have multiple sales. A region with no sales should be also returned. Use 0 for average sales per employee for such a region when calculating the 2nd and the 3rd column.

See the example case for more details.

As a part of the route planner, the routeExists method is used as a quick filter if the destination is reachable, before using more computationally intensive procedures for finding the optimal route.

The roads on the map are rasterized and produce a matrix of boolean values - true if the road is present or false if it is not. The roads in the matrix are connected only if the road is immediately left, right, below or above it.

Finish the routeExists method so that it returns true if the destination is reachable or false if it is not. The fromRow and fromColumn parameters are the starting row and column in the mapMatrix. The toRow and toColumn are the destination row and column in the mapMatrix. The mapMatrix parameter is the above mentioned matrix produced from the map.

For example, for the given rasterized map, the code below should return true since the destination is reachable:

boolean[][] mapMatrix = {
    {true,  false, false},
    {true,  true,  false},
    {false, true,  true}
};
        
routeExists(0, 0, 2, 2, mapMatrix);