20+ Sdet-I Interview Questions and Answers

Count occurrences of two nodes with same horizontal distance in a binary tree

• Traverse the tree using BFS or DFS and keep track of horizontal distance of each node

• Store nodes with same horizontal distance in a hash table and increment count if collision occurs

• Recursively traverse left and right subtrees with updated horizontal distance

• Time complexity: O(n), Space complexity: O(n)

Check if any 3 elements in an array add up to a given number

• Sort the array in ascending order

• Use nested loops to iterate through all possible combinations of 3 elements

• Check if the sum of the 3 elements equals the given number

• Return true if a match is found, else false

Considerations for developing an application for computer aided competitive exams

• User-friendly interface for easy navigation

• Accurate and reliable question bank

• Timed tests to simulate real exam conditions

• Option to save and resume tests

• Detailed performance analysis and feedback

• Compatibility with different devices and operating systems

• Regular updates and bug fixes

• Developer should consider the security of the application to prevent cheating

• User perspective: The application should...read more

Reverse every 3 nodes in a singly linked list using recursion

• Create a recursive function that takes in a node and a count

• If count is less than 3, return the node

• Reverse the first 3 nodes and call the function recursively with the 4th node and count 1

• Connect the reversed nodes to the rest of the list

• Return the new head of the reversed list

Java program to find tall palindrome strings from an array of strings

• Loop through the array of strings

• Check if each string is a palindrome

• Keep track of the tallest palindrome strings found

Code to reverse a string while preserving word positions

• Split the string into words using space as delimiter

• Reverse the order of words

• Join the words back into a string with space as delimiter

Test methods for stress testing of Furniture class

• Create a large number of Furniture objects and check for memory leaks

• Simulate heavy usage by continuously calling methods and check for performance issues

• Test the Furniture class with maximum allowed input values and check for any errors or crashes

Use a stack to find the next greater element for each item in an array efficiently.

• Initialize an empty stack and an output array of the same size as the input.

• Iterate through the array from right to left.

• For each element, pop elements from the stack until you find a greater element or the stack is empty.

• If the stack is not empty, the top element is the next greater element; otherwise, it's -1.

• Push the current element onto the stack for future comparisons.

• Example: For input [4...read more

Check if two binary trees are mirrors by comparing their structure and node values recursively.

• Two trees are mirrors if their root nodes are equal.

• The left subtree of one tree must be a mirror of the right subtree of the other tree.

• Recursively check the left and right subtrees for both trees.

• Example: Tree A (1, 2, 3) and Tree B (1, 3, 2) are mirrors.

This method prints the boundary nodes of a binary tree in a specific order.

• 1. Start from the root node and print it.

• 2. Print the left boundary (excluding leaf nodes).

• 3. Print all leaf nodes from left to right.

• 4. Print the right boundary (excluding leaf nodes) in reverse order.

• Example: For a tree with root 1, left child 2, right child 3, the output would be: 1, 2, 4, 5, 3.

Given a number, find the nearest perfect square using modified binary search.

• Start with low=0 and high=num.

• While low<=high, find mid=(low+high)/2.

• If mid*mid==num, return mid.

• If mid*mid

• If mid*mid>num, update high=mid-1.

• Return the closest perfect square to num.

Delete removes specific rows from a table while truncate removes all rows from a table.

• Delete is a DML command while truncate is a DDL command.

• Delete can be rolled back while truncate cannot be rolled back.

• Delete is slower than truncate as it logs each row deletion while truncate does not.

• Delete can have a WHERE clause to specify which rows to delete while truncate deletes all rows.

• Example: DELETE FROM table_name WHERE column_name = value;

• Example: TRUNCATE TABLE table_name;

Toggle 0s to 1s, 1s to 0s, and 2s to 2s in a binary string.

• Iterate through each character in the string.

• If the character is '0', change it to '1'. Example: '010' -> '101'.

• If the character is '1', change it to '0'. Example: '101' -> '010'.

• If the character is '2', keep it as '2'. Example: '120' -> '120'.

• Return the modified string after toggling.

Reverse a string while preserving the positions of special characters and spaces.

• Iterate through the string from both ends using two pointers

• Swap characters if both are alphabets or both are special characters

• Continue until the pointers meet in the middle

A program to determine if given strings are an anagram.

• Convert each string to lowercase and remove any non-alphabetic characters.

• Sort the characters in each string.

• Compare the sorted strings to check if they are equal.

To create a table in a database, use the CREATE TABLE statement.

• Specify the table name and column names with their data types.

• Add any constraints or rules for the table.

• Example: CREATE TABLE customers (id INT, name VARCHAR(50), email VARCHAR(100));

To build a framework from scratch using Appium for automated testing of mobile applications.

• Set up Appium server and desired capabilities

• Create test scripts using Appium commands

• Implement page object model for better organization

• Use assertions to validate test results

• Integrate with CI/CD tools for continuous testing

• Handle different types of locators for elements

• Implement error handling and reporting mechanisms

The problem involves solving a question related to two matrices, likely involving operations like addition, multiplication, or comparison.

• Identify the dimensions of both matrices before performing operations.

• For addition, both matrices must have the same dimensions (e.g., 2x2 + 2x2).

• For multiplication, the number of columns in the first matrix must equal the number of rows in the second (e.g., 2x3 * 3x2).

• Consider edge cases, such as empty matrices or matrices filled with zero...read more

To test a FB login page, I would verify functionality, security, and compatibility.

• Verify login functionality by entering valid and invalid credentials

• Test for security by checking for SSL encryption, password hashing, and account lockout

• Ensure compatibility by testing on different browsers and devices

Multithreading in Java allows multiple threads to execute concurrently, improving performance and responsiveness.

• Multithreading in Java is achieved by extending the Thread class or implementing the Runnable interface.

• Threads share the same memory space, so synchronization is necessary to prevent data corruption.

• Java provides synchronized keyword, locks, and atomic classes for thread synchronization.

• Concurrency issues like deadlock, race conditions, and thread interference can...read more

Implement Stack class in Java.

• Create a class with an array to store elements

• Implement push() method to add elements to the stack

• Implement pop() method to remove and return top element

• Implement peek() method to return top element without removing

• Implement isEmpty() method to check if stack is empty

Appium automation framework design involves selecting programming language, test framework, page object model, and reporting tools.

• Select programming language (e.g. Java, Python) for writing test scripts

• Choose test framework (e.g. TestNG, JUnit) for organizing and executing tests

• Implement page object model for better code maintainability and reusability

• Integrate reporting tools (e.g. ExtentReports, Allure) for generating test reports

findElements returns a list of web elements matching the locator, while findElement returns the first matching element.

• findElements is useful when there are multiple elements with the same locator

• findElement throws NoSuchElementException if no element is found

• findElements returns an empty list if no element is found

• Example: List links = driver.findElements(By.tagName("a"));

• Example: WebElement username = driver.findElement(By.id("username"));

Water level problem - how to measure water level in a tank?

• Use a water level sensor

• Install a float switch

• Use a pressure sensor

• Measure the weight of the water in the tank

• Use ultrasonic sensors to measure the distance between the water surface and the top of the tank

Finding the median value from an array of strings.

• Sort the array in ascending order

• If the array length is odd, return the middle element

• If the array length is even, return the average of the middle two elements