Uplers R&D Engineer Interview Questions and Answers

Given a 2D matrix with doors and walls, fill distance matrix with minimum distance to the nearest door.

• Iterate through the matrix and find the doors

• Use Breadth-First Search (BFS) to calculate the minimum distance from each cell to the nearest door

• Update the distance matrix with the minimum distances

Find kth smallest element in unordered array with O(1) space

• Use the QuickSelect algorithm to partition the array and find the kth smallest element

• Choose a pivot element and partition the array into two subarrays

• Recursively partition the subarray that contains the kth smallest element

• Repeat until the pivot element is the kth smallest element

• Time complexity: O(n) average case, O(n^2) worst case

To find friends of friends who are not already friends with you, we can first find your friends and then their friends excluding yourself and your friends.

• Get your list of friends

• For each friend, get their list of friends

• Exclude yourself and your friends from the final list of friends of friends

Function to check if a string of parenthesis is balanced

• Use a stack to keep track of opening parenthesis

• If a closing parenthesis is encountered, pop from stack and check if it matches

• If stack is empty and a closing parenthesis is encountered, return False

• If all parenthesis are matched and stack is empty, return True

Count the occurrences of words in a paragraph.

• Split the paragraph into words using whitespace as a delimiter.

• Create a dictionary to store the count of each word.

• Iterate through the words and increment the count in the dictionary.

• Return the dictionary with the word counts.

Find common elements out of two sorted array

• Use two pointers to traverse both arrays simultaneously

• Compare elements at each pointer and move the pointer of the smaller element

• If elements are equal, add to common elements list and move both pointers

• Stop when either pointer reaches end of array

Convert a Binary Search Tree to a Doubly Linked List.

• Create a DLL node class with left, right, and data fields.

• Traverse the BST in-order and add each node to the DLL.

• Adjust the left and right pointers of each node to create the DLL.

• Return the head of the DLL.

The task is to fill the 'next' field of each node in a binary tree to point to the next node at the same level.

• Use a level order traversal to process the tree nodes.

• Maintain a queue to store the nodes at each level.

• For each node, set its 'next' field to the next node in the queue.

• If a node is the last node at its level, set its 'next' field to NULL.

To find anagrams of a given word in a dictionary, use a hash table to store sorted versions of each word as keys and their corresponding original words as values.

• Create a hash table to store the anagrams

• Iterate through each word in the dictionary

• Sort the characters of the word and use it as a key in the hash table

• If the key already exists, add the word to the list of values for that key

• Print the list of values for the

Suggest a data structure for efficient search of a string in 10 files and print line number and file if string appears more than once.

• Use a hash table to store the file name and line number of each occurrence of the string.

• Iterate through each file and for each line, check if the string is present and update the hash table accordingly.

• Print the hash table entries for the string.

Amazon is the right place for me because of its innovative culture, vast resources, and opportunities for growth.

• Amazon's innovative culture aligns with my passion for pushing boundaries and finding creative solutions.

• The company's vast resources provide the necessary tools and support to develop and deliver high-quality software.

• Amazon offers numerous opportunities for growth and career advancement, allowing me to con...read more