Data Structures and Algorithms for Interviews
Bridge the gap between knowing basic data structures and recognizing algorithmic patterns under interview conditions. Learn how to diagnose problem types, formulate optimal state transitions, and defend time-space tradeoffs with precision.
Like Duolingo, but for Data Structures and Algorithms for Interviews. Tomo turns the whole topic into a game you play five minutes a day, until it actually sticks.
25 levels across 3 sections, about 50 minutes end to end, roughly 10 days at five minutes a day. It moves through Linear Patterns and Window State, Hierarchies and Network Traversals, and Strategic Search and Optimization. It assumes you already know the basics.
Free forever · No credit card · iPhone & Android
Key ideas in Data Structures and Algorithms for Interviews
- A sliding window moves left and right boundaries strictly forward across the array.
- Reusing the prior slice sum by adding the new entry and dropping the stale one avoids re-summing.
- Because each boundary visits an element at most once, total runtime stays linear at O(N).
- The right pointer expands forward to ingest new elements until the window becomes valid.
- Candidate lengths are recorded while the current window satisfies the target criteria.
- The left pointer contracts forward to remove excess elements and find the minimal valid span.
- In a sorted array, the current right element paired with any inner element will still exceed the target.
- Decrementing the right pointer safely discards impossible candidate pairs without inspecting them all.
- Opposing pointers exploit monotonicity in sorted inputs to converge inward in O(N) time.
- A 2:1 pointer speed ratio places the slow pointer at the exact midpoint when the fast pointer reaches the end.
- Floyd's cycle-finding algorithm guarantees two pointers inside a loop must meet within one full cycle traversal.
- Resetting one pointer to the head after a collision locates the loop entrance in linear time and O(1) space.
- Adding an incoming element or removing an outgoing element takes O(1) map hash-update operations.
- A separate match-count tracker updates in O(1) whenever an individual character meets its threshold.
- Rescanning the entire frequency dictionary on every shift ruins the amortized O(N) time guarantee.
- A prefix array precomputes running totals in O(N) time to answer any range sum query in O(1) time.
You've tried the other tabs
Thirty open tabs. Four facts you actually kept.
You watched. You nodded. By Sunday it was gone.
One answer, then back to scrolling.
Eight weeks. You meant to finish. You didn't.
Tomo gives Data Structures and Algorithms for Interviews the Duolingo treatment: levels, streaks, and quick quizzes that test what you just learned. That game loop is what the tabs above never had, so it's the one you actually finish.
Here's what playing it feels like
A real question from this course. Take your best guess.
When sliding a 4-item window one step right, how should you update the window's sum efficiently?
Get it right to open this lesson and 24 more in the app.
How to learn Data Structures and Algorithms for Interviews, step by step
Go in order. 25 short levels across 3 sections, about 50 minutes in all, five minutes a day.
- 1
Linear Patterns and Window State
- Sliding Window and Two Pointers
- Prefix Accumulation and Hash Lookups
- Monotonic Structures and Priority Queues
- 2
Hierarchies and Network Traversals
- Binary Trees and Subtree Contracts
- Graph Modeling, Connectivity, and Dependencies
- 3
Strategic Search and Optimization
- Binary Search on Monotonic Predicates
- Backtracking and Combinatorial Pruning
- Dynamic Programming: State and Tabulation
3 sections · 8 units · 25 levels. Built to play, not to enroll.
Questions about Data Structures and Algorithms for Interviews
How do I learn Data Structures and Algorithms for Interviews?
Go in order: start with Linear Patterns and Window State, then Hierarchies and Network Traversals, then Strategic Search and Optimization. On Tomo that's 25 short levels, about 50 minutes in all, played five minutes a day. Start free and play the first level in under a minute.
Is there a Duolingo-style app for Data Structures and Algorithms for Interviews?
Yes. Tomo works like Duolingo: short daily lessons, streaks and quick quizzes. Data Structures and Algorithms for Interviews is one of its free courses, and you can type any other topic to get a course of your own.
Is the Data Structures and Algorithms for Interviews course free?
Yes. Data Structures and Algorithms for Interviews is playable on Tomo's free plan, which doesn't expire. No credit card, no waitlist. Download the app and start your first lesson.
How long does it take to learn Data Structures and Algorithms for Interviews?
25 levels across 3 sections, about 50 minutes of play in total. It's built for five minutes a day, so you finish it a little at a time instead of all at once.
Do I need any background to start Data Structures and Algorithms for Interviews?
No. It's pitched at an intermediate level, so it starts where you are and builds up. If you can tap a phone, you can start.
Tomo is in ChatGPT
Tomo is also a ChatGPT plugin: the same playable courses, built and played inside your chat.
Add Tomo to ChatGPT- What to ask
- “Make me a Tomo course on black holes.” “Turn this chat into a Tomo course.”
- What you get
- Quick questions with instant feedback, hearts and stars, ready to play in about a minute.
- Where it goes
- No sign-up to start. Connect your Tomo account and your streak carries on in the app.
You pick the voice
Data Structures and Algorithms for Interviews is taught in the Professor style: clear, structured, thorough. Want a different feel? In the app you can spin up the same topic in any of Tomo's teaching styles. Same facts, totally different vibe.
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