Representative Randomized problems
Implement a data structure supporting insert, delete, and getRandom in average O(1) using array plus hash mapping.
Open problem page#381 Insert Delete GetRandom O(1) - Duplicates allowedThis problem challenges you to design a data structure that supports insertion, removal, and random access with O(1) time complexity while allowing duplicates.
Open problem page#382 Linked List Random NodeSelect a random node from a singly linked list ensuring uniform probability using efficient pointer techniques and reservoir sampling.
Open problem page#384 Shuffle an ArrayShuffle an Array requires designing a class to randomly permute an integer array while ensuring all permutations are equally likely.
Open problem page#398 Random Pick IndexRandom Pick Index involves selecting a random index of a target number in an array with possible duplicates.
Open problem page#470 Implement Rand10() Using Rand7()Generate uniform random numbers from 1 to 10 using only rand7(), applying rejection sampling for consistent probability distribution.
Open problem page#478 Generate Random Point in a CircleGenerate Random Point in a Circle requires creating a uniform random point inside a circle using math and geometry principles efficiently.
Open problem page#497 Random Point in Non-overlapping RectanglesDesign an algorithm to pick random points within non-overlapping rectangles using binary search and reservoir sampling.
Open problem page#519 Random Flip MatrixDesign an optimized algorithm to randomly flip an index in a matrix, using hash tables and math for efficient random selection.
Open problem pageRandomized interview questions usually collapse into a small set of repeatable moves. This page groups those GhostInterview problem pages together so you can stay inside one pattern family, compare representative questions, and practice explanations that transfer across multiple prompts. If you are trying to sharpen one interview weakness instead of browsing the entire library, start here.
Why Randomized Matters In Coding Interviews
Interviewers rarely care about the label alone. They care about whether you can recognize when the Randomized pattern applies, explain why it applies, and avoid the failure modes that usually show up under time pressure. That is why this page focuses on the family of problems rather than a single isolated example.
Pattern families that show up here
- Array scanning plus hash lookup
- Array plus Math
- Binary search over the valid answer space
Use this page to narrow the session
Start from this topic hub, choose one or two representative problems, and then open the detailed problem pages only after you know which version of the pattern you want to reinforce.
How To Practice This Topic
The best workflow is to keep the prep block narrow. Pick one easy or medium problem to confirm the base pattern, then one medium or hard problem to test whether the explanation still holds when the constraints tighten. Once the logic is stable, move into GhostInterview to rehearse the live explanation flow.
Focus on transfer, not title count
Solving more Randomized titles is less useful than understanding how the same move changes across examples. Try to describe what stays the same and what changes from one problem to the next.
Use the problem page when you want the exact breakdown
This topic hub is the discovery layer. The single-problem pages are where you get the answer-first summary, examples, constraints, approach, complexity, pitfalls, and solver CTA.
How GhostInterview Fits
GhostInterview works best after you know which pattern family you are inside. Use this page to choose the right Randomized problem, then use the solver to get the answer path, complexity framing, and follow-up support without switching into a generic study flow.
FAQ
What does the Randomized topic usually test in interviews?
Randomized questions usually test whether you can spot the underlying pattern quickly, explain the trade-offs, and move from intuition to implementation without losing clarity.
How should I use this Randomized topic page?
Use it as a pattern hub. Start with the representative problems on this page, compare the common approach, and then open the exact problem page when you want the full breakdown.
How many GhostInterview problem pages are in the Randomized group?
This topic page currently groups 12 indexed GhostInterview problem pages under the Randomized family.
Should I practice this topic before harder patterns?
That depends on your current gaps. If Randomized is already a weak spot in interviews, it is usually better to stabilize it first before moving into more advanced or less frequent patterns.
Where does GhostInterview fit once I pick a Randomized problem?
The topic page narrows the pattern family. The problem page gives the exact breakdown. GhostInterview is the solver layer when you need direct help with execution, complexity, and follow-up handling.
Stay close to the same reasoning family
Need direct help once you choose a Randomized problem?
Use GhostInterview as the solver layer after you select the exact prompt. Capture the question, get the answer path and complexity framing, and keep the workflow inside the same topic family.