ServiceNow Senior Software Engineer Interview Questions, Process, and Tips

Use dynamic programming to find the longest palindromic substring in a given string.

• Iterate through the string and expand around each character to find palindromes.

• Store the length of the longest palindrome found so far.

• Return the substring based on the start and end indices of the longest palindrome.

To serialize and deserialize a tree, use a recursive approach to traverse the tree and store the data in a suitable format.

• Use pre-order traversal to serialize the tree by storing the node values in a list or string.

• For deserialization, reconstruct the tree by recursively building nodes from the serialized data.

• Consider using JSON or XML format for serialization to easily store and retrieve tree structure.

Use regex library to match given regex with string.

• Use a regex library like re in Python to match the given regex with the string.

• Check if the regex matches the string using the library functions.

• Handle cases where the regex contains special characters like . and * appropriately.

Throttling is a technique used to control the rate of requests sent to a server.

• Throttling helps prevent server overload by limiting the number of requests processed at a time.

• Implementing a throttle function involves setting a maximum request rate and delaying excess requests.

• Example: Implementing a throttle function in a web application to limit the number of API calls made to a third-party service.

• Example: Throttlin...read more

Sort the squares of elements in a sorted array and return the sorted response.

• Iterate through the array and square each element.

• Store the squared values in a new array.

• Sort the new array and return it.

A promise is a commitment to do something in the future, typically used for asynchronous operations in JavaScript.

• Promises are used to handle asynchronous operations in JavaScript.

• They represent a value that may be available now, in the future, or never.

• Promises have three states: pending, fulfilled, or rejected.

• Example: new Promise((resolve, reject) => { setTimeout(() => resolve('Done!'), 1000); });

Event loop is a mechanism that allows for asynchronous execution of code by managing the order of events in a single thread.

• Event loop continuously checks the call stack for any functions that need to be executed, and processes them in a non-blocking manner.

• Different types of queues in event loop include microtask queue (Promise callbacks), macrotask queue (setTimeout, setInterval callbacks), and animation frame queue

Virtual DOM is a lightweight copy of the actual DOM, used to improve performance by minimizing direct manipulation of the real DOM.

• Virtual DOM is a concept used in frameworks like React to optimize rendering performance.

• Changes are first made to the virtual DOM, which is then compared to the real DOM to identify the minimal updates needed.

• This approach reduces the number of actual DOM manipulations, resulting in faster...read more

Check if a linked list is circular by using two pointers moving at different speeds.

• Initialize two pointers, slow and fast, both pointing to the head of the linked list.

• Move slow pointer by one node and fast pointer by two nodes in each iteration.

• If the fast pointer reaches the end of the list or meets the slow pointer, the list is circular.