Paytm Software Engineer Interview Questions and Answers

Search for a target value in a sorted matrix efficiently.

• Start from the top right corner and move left or down based on comparison with target value

• Utilize the sorted nature of the matrix to eliminate certain rows or columns

• Implement binary search for more efficient search in each row or column

HashMap is non-synchronized and allows null values, while Hashtable is synchronized and does not allow null keys or values.

• HashMap is non-synchronized, meaning it is not thread-safe, while Hashtable is synchronized and thread-safe.

• HashMap allows null values and one null key, while Hashtable does not allow null keys or values.

• HashMap is generally preferred for non-thread-safe applications, while Hashtable is used i...read more

MongoDB is a NoSQL database while SQL is a relational database management system.

• MongoDB is schema-less, allowing for flexible data models.

• SQL databases use structured query language for defining and manipulating data.

• MongoDB is better suited for unstructured or semi-structured data, while SQL is better for structured data.

• SQL databases are ACID compliant, ensuring data integrity, while MongoDB sacrifices some ACI...read more

Convert a Binary Search Tree (BST) into a new BST containing only nodes within a given range.

• Perform inorder traversal of the original BST and only add nodes within the given range to the new BST.

• Recursively call the function on left and right subtrees while checking the node values against the range.

• Adjust the pointers of the nodes to form the new BST.

Find an element in a rotated sorted array using binary search for efficient lookup.

• A rotated sorted array is created by taking a sorted array and rotating it at a pivot point.

• Example: [4, 5, 6, 7, 0, 1, 2] is a rotated version of [0, 1, 2, 4, 5, 6, 7].

• Use binary search to find the target element, adjusting the search range based on the pivot.

• If the middle element is greater than the rightmost element, the pivot is...read more

Quick sort is an efficient sorting algorithm that uses a divide-and-conquer approach to sort elements in an array.

• 1. Choose a 'pivot' element from the array.

• 2. Partition the array into two sub-arrays: elements less than the pivot and elements greater than the pivot.

• 3. Recursively apply the above steps to the sub-arrays.

• 4. Combine the sorted sub-arrays and the pivot to get the final sorted array.

• Example: For array ...read more

Merge sort using linked list is a sorting algorithm that divides the list into smaller sublists, sorts them, and then merges them back together.

• Create a function to merge two sorted linked lists

• Divide the linked list into two halves using slow and fast pointers

• Recursively sort the two halves

• Merge the sorted halves back together