Skill guide

Data Structures

Knowing which structure fits a problem: and its trade-offs: is the single most tested skill in technical interviews.

Skill levels

beginner

  • Arrays, strings, linked lists
  • Stacks and queues
  • Basic time complexity (Big O)

intermediate

  • Hash maps and sets
  • Trees (binary, BST) and traversal
  • Heaps/priority queues

Job-ready

  • Graphs (BFS/DFS, weighted)
  • Tries and when to use them
  • Choosing the right structure quickly under interview pressure

How to prove it

  • A completed assessment
  • Implementations of 3+ structures from scratch
  • Solved and explained 30+ problems spanning structures

Common interview questions

Mentor opinion
  • When would you use a heap instead of sorting?
  • Explain how a hash map handles collisions.
  • How do you detect a cycle in a linked list?