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DSA patterns AI roles still ask

  • Coding
  • Asked often
  • About 2 h 30 min to learn
  • 3 vetted resources
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What this topic covers

Most Applied AI and LLM engineer loops still include at least one general coding round, but it is rarely a hard dynamic-programming puzzle; it leans on a small set of patterns: array and string scans, hash maps for counting and lookup, two pointers and sliding windows, BFS and DFS over grids and graphs, and heaps for top-k. Interviewers want to see you name the pattern, state the complexity, handle empty and single-element inputs, and write clean Python without hesitation. This topic is about recognising which pattern a prompt maps to and having a template for each one ready, not grinding hundreds of problems.

You’re ready when you can

What interviewers check, from the resources below.

  • Name the six High-priority topics and say which pattern each usually tests
  • List the corner cases you check before coding any array or string problem
  • Explain why a hash map is the first data structure to consider for an O(n) solution
  • State a problem's time and space complexity out loud before writing code
  • Solve two linked questions from each of the six topics, each within 25 minutes
  • State the time and space complexity out loud before writing code, every time
  • Name the pattern a new problem calls for (two pointers, sliding window, BFS, heap) within a minute
  • Explain the brute-force approach before optimising it
  • Implement BFS and DFS over a 2-D grid from memory with a visited set and bounds checks
  • Explain why BFS uses a deque and what goes wrong with list.pop(0)

What to study, in order

Each link opened and checked by hand; the date says when.

  1. Start here

    Data structures and algorithms study cheatsheets for coding interviews (opens in a new tab)

    Tech Interview Handbook · Yangshun Tay · 15 min · Free · checked 21 Oct 2026

    Why
    It ranks topics by how often they show up in interviews, which is exactly the triage an Applied AI candidate with limited DSA time needs.
    What to read
    Read “Contents of each study guide”, “Study guides list” (note the High / Mid / Low priority tags) and “General interview tips”. Then open the High-priority Array, String and Graph guides plus the Mid-priority Hash Table and Heap guides from the list.
    What to skip
    “Recommended courses”; the linked per-topic guides are enough and the courses are paid.

  2. Free alternative

    Coding interview study plan - what to study and practice based on time left (opens in a new tab)

    Tech Interview Handbook · Yangshun Tay · 240 min · Free · checked 22 Oct 2026

    Why
    A coding round opens most loops, Amazon's included, and speed only comes from solving problems out loud. This page budgets hours per topic and links each topic's practice questions on LeetCode (75 in all), so you practise the right ones in the time you have.
    What to read
    Read “Recommended preparation time and approach”, then work through the questions linked from the “Week 1 - 4” table for Array, String, Hash Table, Graph, Heap and Tree: two per topic, 25 minutes each, out loud. Restate the problem, ask about edge cases, give the brute force, then optimise and state the complexity before you type.
    What to skip
    “Week 5 - 12: In-depth practice” unless your loop has two or more coding rounds; the self-introduction and mock-interview sections are covered by the behavioral topic.

  3. Go deeper

    Graph cheatsheet for coding interviews (opens in a new tab)

    Tech Interview Handbook · Yangshun Tay · 40 min · Free · checked 21 Oct 2026

    Why
    Grid and graph BFS/DFS is the medium-difficulty question AI teams reach for most, and this page has the Python templates to drill until they're automatic.
    What to read
    Read “Graph representations”, “Corner cases” and all of “Graph search algorithms” (“Depth-first search”, “Breadth-first search”, “Topological sorting”). Then solve the three “Essential questions”.
    What to skip
    “Learning resources” and “Recommended courses”; the questions marked LeetCode Premium under “Recommended practice questions”.

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