Practice Test GeeksPractice Test Geeks

CodeSignal Technical Assessment Cheat Sheet 2026

The 30 highest-yield CodeSignal Technical Assessment facts, distilled from real exam questions. Print it, save it as a PDF, or study it here ā€” free, no sign-up.

50 questions
70 min time limit
50% to pass
  1. In a REST API, which HTTP status code indicates that the client's request was syntactically correct but semantically invalid (e.g., a business rule violation)? ā†’ 422 Unprocessable Entity
  2. What is the amortized time complexity per operation for Union-Find with both path compression and union by rank? ā†’ O(alpha(N)) ā€” inverse Ackermann
  3. Which of the following is an example of a graph traversal algorithm? ā†’ Depth-First Search (DFS)
  4. An undirected graph has 5 vertices and is fully connected (complete graph). How many edges does it have? ā†’ 10
  5. In a CodeSignal challenge involving a binary search tree, you must find the lowest common ancestor of two nodes. What traversal approach is most direct? ā†’ Exploit BST ordering: recurse left if both nodes are smaller, right if both are larger
  6. In exponential search, what is the first step before performing binary search? ā†’ Find a range [2^k, 2^(k+1)] where the target may exist
  7. In a CodeSignal challenge, you must validate a set of parentheses including '(', ')', '{', '}', '[', ']'. Which structure is essential? ā†’ Stack (LIFO)
  8. When does the Floyd-Warshall algorithm apply best? ā†’ All-pairs shortest paths on dense graphs
  9. What is the worst-case time complexity of QuickSort when the pivot is always the smallest or largest element? ā†’ O(nĀ²)
  10. A doubly linked list differs from a singly linked list because each node in a doubly linked list: ā†’ Has a pointer to both next and previous nodes
  11. In a relational database, what is a foreign key constraint used for? ā†’ Enforcing referential integrity between two tables
  12. What does 'optimal substructure' mean in the context of dynamic programming? ā†’ The optimal solution to the problem contains optimal solutions to its subproblems
  13. What does ''.join(reversed('hello')) return? ā†’ 'olleh'
  14. What is the output of `print(0.1 + 0.2 == 0.3)` in Python? ā†’ False
  15. What is the time complexity of accessing an element in an array by index? ā†’ O(1)
  16. A CodeSignal challenge requires implementing an LRU (Least Recently Used) cache with O(1) get and put. Which combination of data structures achieves this? ā†’ Hash map + doubly linked list
  17. Which sorting algorithm is most efficient for sorting a nearly-sorted array with only a few elements out of place? ā†’ Insertion Sort
  18. What is the space complexity of a recursive depth-first search on a graph with V vertices and E edges? ā†’ O(V)
  19. What does amortized O(1) mean for a dynamic array's append operation? ā†’ The average cost per append over a sequence of operations is O(1)
  20. A CodeSignal problem asks for the number of ways to make change for an amount using given coin denominations. Which DP formulation is correct? ā†’ dp[i] += dp[i - coin] for each coin ā‰¤ i, starting with dp[0] = 1
  21. What is the worst-case time complexity of searching for a value in an unbalanced Binary Search Tree? ā†’ O(n)
  22. Which problem can be solved with the sliding window technique? ā†’ Maximum sum subarray of size k
  23. You are solving a CodeSignal task on interval merging. Given a list of intervals sorted by start time, what is the key condition to merge two intervals? ā†’ The start of the next interval is less than or equal to the end of the current interval
  24. What is the time complexity of solving the 0/1 knapsack problem with n items and capacity W using dynamic programming? ā†’ O(nW)
  25. Which input for the function isPalindrome returns True? ā†’ isPalindrome("level")
  26. In the context of searching, what is an interpolation search and when does it outperform binary search? ā†’ It searches by value interpolation; O(log log n) on uniformly distributed data
  27. An API gateway receives 50,000 requests/sec. Which rate-limiting algorithm smooths traffic most evenly without bursting? ā†’ Leaky bucket
  28. What is the average-case time complexity of hash table lookup? ā†’ O(1)
  29. Which operation on a stack is used to view the top element WITHOUT removing it? ā†’ peek()
  30. How many set bits does the number 12 (binary 1100) have? ā†’ 2
Turn these facts into recall:
šŸƒ CodeSignal Technical Assessment FlashcardsšŸ“š Full Study Guide