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12 questions

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CodingMediumLeetCode 362
Design Hit Counter
Design a hit counter that records timestamps of hits and returns the number of hits in the past 5 minutes (300 seconds). The challenge is…
Companies: Adyen, Apple, Cisco, Databricks +5
Array · Binary Search · Data Stream · Design
Last reported Nov 2026
Open workspace
CodingEasyLeetCode 387
First Unique Character in a String
Return the index of the first character in s that occurs exactly once (or -1 if none). This is typically solved by counting character frequencies…
Companies: Apple, Goldman Sachs
Counting · Hash Table · Queue · String
Last reported Sep 2026
Open workspace
CodingMediumLeetCode 341
Flatten Nested List Iterator
Given a nested list where elements may be integers or sublists, implement a NestedIterator with next() and hasNext() that returns all integers in depth‑first, left‑to‑right…

Companies: Adobe, LinkedIn

Depth-First Search · Design · Iterator · Queue

Last reported Aug 2026

CodingHardLeetCode 239

Sliding Window Maximum

Given an integer array and a window size k, return the maximum value for each contiguous subarray (sliding window) as it moves one step to…

Companies: Amazon, Bloomberg, D. E. Shaw, Expedia +7

Array · Heap (Priority Queue) · Monotonic Queue · Queue

Last reported Jun 2026

CodingMediumLeetCode 1429

First Unique Number

Design a data structure that, given an initial list and a stream of added numbers, returns the first integer that appears exactly once at any…

Companies: Uber

Array · Data Stream · Design · Hash Table

Last reported Jun 2026

CodingMediumLeetCode 1438

Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit

Find the length of the longest contiguous subarray whose maximum minus minimum is ≤ limit; the key challenge is maintaining the window's current min and…

Companies: MongoDB, Uber

Array · Heap (Priority Queue) · Monotonic Queue · Ordered Set

Last reported Apr 2026

CodingHardLeetCode 2444

Count Subarrays With Fixed Bounds

Count the number of contiguous subarrays whose minimum equals minK and maximum equals maxK. The main challenge is to efficiently (O(n)) scan the array, partitioning…

Companies: Adobe, Uber

Array · Monotonic Queue · Queue · Sliding Window

Last reported Apr 2026

CodingEasyLeetCode 346

Moving Average from Data Stream

Design a data structure that, given a continuous stream of numbers and a fixed window size k, returns the moving average of the last k…

Companies: Box, Google, Meta, Spotify

Array · Data Stream · Design · Queue

Last reported Mar 2026

CodingHardLeetCode 862

Shortest Subarray with Sum at Least K

Find the length of the shortest contiguous subarray whose sum is at least k, or return -1 if none exists. Because nums can contain negative…

Companies: Meta

Array · Binary Search · Heap (Priority Queue) · Monotonic Queue

Last reported Jan 2025

CodingMediumLeetCode 622

Design Circular Queue

Implement a fixed-size circular queue (ring buffer) supporting enqueue, dequeue, Front/Rear, isEmpty and isFull operations without using built-in queue types. The core…

Companies: NVIDIA

Array · Design · Linked List · Queue

CodingMediumLeetCode 3829

Design Ride Sharing System

Companies: Rippling

Data Stream · Design · Hash Table · Queue

CodingMediumLeetCode 1823

Find the Winner of the Circular Game

Given n people seated in a circle, repeatedly remove every k-th person clockwise until one remains and return their label — the classic Josephus problem…

Companies: Goldman Sachs

Array · Math · Queue · Recursion