This Bloomberg question asks you to design a deque-like data structure that supports inserting and removing from both ends, plus querying its size, all in constant time. The natural approach is to use a doubly linked list (or dynamic circular array) and maintain head, tail, and size fields so each operation touches only a few…

This Google interview problem simplifies a computer vision task: given a frame represented as an m×n matrix of 0s and 1s, where a spine tag corresponds to a square submatrix of 1s, determine how to detect that square quickly and efficiently. The challenge typically lies in finding the top-left coordinate and size of the square…

This Google interview problem describes an evacuation scenario: multiple flights leave the island tomorrow, and every islander has their own arrival time at the airport. Assuming planes fill up in departure-time order and seats are taken by whoever arrives earlier, you must compute the latest time you personally can arrive at the airport and still…

This Google problem asks you to determine whether a“needle”appears in a“haystack,”but with a twist: non-standard characters such as é, ë, æ, or å must be converted according to a given transliteration map before matching. The map can map one character to multiple English characters (e.g., “æ” → “ae”), so matching is not just one-to-one replacement…

“””Implement a restaurant waitlist data structure. It should support the following features: A party of customers can join the waitlist.A previously joined party can leave the waitlist at any time.The restaurant can ask the data structure for the first party that fits a given table size (a table size is given as an argument).“”” This…

“””Write a memory allocation function (and corresponding free function)that returns a block of memory aligned to the specified alignment value.You may assume that the alignment is a power of 2 (1, 2, 4, 8, 16, …).“”” This Google systems-level question asks you to implement your own malloc-like function that guarantees the returned pointer is aligned…

“””We have an embedded environment with a very simple operating system. Part of the facilities provided to us is a single hardware timer.The goal is to implement multiple timers, each with their own callback, based on this single timer.The hardware timer can be set with the following function:void set_hw_timer(int relative_timeout_ms);After relative_timeout_ms milliseconds have elapsed, the…

“””// Write a node class to be used in a tree. A Node should contain exactly one integer and have zero or more children.“”” “””Define: a “descending tree” is a tree such that for each node n, the value of n is larger than the value of any descendant of n. Write a function that…

“””You and a friend have received a special gold chain as a gift.The chain links each have an integer weight, not necessarily the same.You and your friend must choose one of the links to be removed and provided to charity, after which the chain will be reconnected.After that, you can choose one place along the…

“””Imagine a log file that abridges chats. An example chat might be: 10:00 <john> hi!10:01 <maria> hello!10:07 <john> can you link the design? where john said 6 total words and maria said 1. Your goal is to present the top N most talkative users in descending order. You need to write a function that takes…

An arithmetic sequence is a list of numbers with a definite pattern. If you take any number in the sequence then subtract it from the previous one, the difference is always a constant. A good arithmetic sequence is an arithmetic sequence with a common difference of either 1 or -1. For example, [4, 5, 6]…

This problem is a standard weighted random selection. Build a prefix-sum array based on city populations and map a random value into one of the prefix intervals. This guarantees output probabilities match the weight distribution, and repeated queries remain efficient. The key is prefix sums plus binary search for fast selection. The BST property allows…

The solution uses a stack to simulate function calls. A“begin”event pushes a new frame and pauses the previous function, while an“end”event pops the function and accumulates its exclusive time based on timestamp differences. Properly tracking the previous timestamp is essential to handle nesting correctly. The VOprep team has long accompanied candidates through various major company OAs and…

Standing on the left side gives the leftmost node of each level, but the ordering must be reversed from bottom to top. Standing on the right side gives the rightmost node level by level from top to bottom. The problem is solved with BFS level traversal and extracting the appropriate visible node at each level….

This is the 2D extension of the range counting problem. Build a 2D prefix-sum matrix pre[i][j] for ones in the rectangle from (0,0) to (i,j), then answer any subgrid query in O(1) time using the inclusion–exclusion formula. It tests understanding of 2D prefix sums and careful boundary handling The VOprep team has long accompanied candidates through various…

This problem is a classic range query task. The optimal solution precomputes a 1D prefix-sum array where prefix[i] stores the number of ones up to index , then each query runs in O(1) time using prefix[end] – prefix[start-1]. It tests preprocessing, time–space trade-offs, and clean API design. The VOprep team has long accompanied candidates through various major…

The task is to evaluate an expression with only + and *, respecting operator precedence. Typical solutions use a stack to accumulate intermediate products, or track the current multiplication block during a single pass. The VOprep team has long accompanied candidates through various major company OAs and VOs, including Meta, Amazon, Citadel, SIG, providing real-time voice assistance,…

A classic weighted random selection question: build a prefix-sum array, generate a random number within the weighted range, and use binary search to find the correct index. Commonly tested in Meta interviews for probability distribution and prefix-sum logic The VOprep team has long accompanied candidates through various major company OAs and VOs, including Meta, Amazon, Citadel, SIG,…

This Meta interview question asks for all root-to-leaf path sums in a binary tree. A depth-first search is used to propagate the running sum, recording values when a leaf is reached. It tests recursion, tree traversal, and handling of leaf conditions. The VOprep team has long accompanied candidates through various major company OAs and VOs, including Meta,…

This problem tests arbitrary-base conversion where the number is stored as a linked list. The core idea is to extract the base-10 value, then repeatedly apply modulo and division to build the new-base list. It evaluates understanding of linked-list big-integer representation and digit extraction logic. The VOprep team has long accompanied candidates through various major company OAs…