How do you reverse an array in-place with O(1) extra space?

Heisenbug logo
TheHeisenBug

Search

Search across questions, learning content, and hands-on projects

Ace Your Next Tech Interview

5,986+ interview questions across 87 technologies — with expert answers, advanced search, AI-powered assistance, personal highlights, structured learning paths, and hands-on practice projects.

5,986+Questions & Answers
87Technologies
AdvancedSearch
Built-inAsk AI
PersonalHighlights
StructuredLearning Paths
Hands-onPractice Projects

Lifetime Access

One-time payment. No subscriptions. Unlock everything, forever.

$19.90USD

or R$49.90 BRL

FeatureFreePremium
Question titlesAllAll
Answers per topicTop 5All
Learning chaptersFirst 5All
Practice projectsFirst 3All
Highlights✓✓
Ask AI—✓
Read tracking✓✓
Search✓✓

Arrays Interview Questions

  1. [JUNIOR] What is an array and how does it differ from other data structures?
  2. [JUNIOR] What are the advantages and disadvantages of using arrays?
  3. [JUNIOR] What is the time complexity for accessing, inserting, and deleting elements in an array?
  4. [MID] What is the two-pointer technique and how is it applied to array problems?
  5. [MID] How do you find a pair of elements in an array that sum to a given target (Two Sum problem)?
  6. [JUNIOR] How do arrays differ from linked lists?
  7. [JUNIOR] What is the difference between fixed-size (static) and dynamic arrays?
  8. [MID] What is the sliding window technique and how does it improve array problem performance?
  9. [MID] How do you merge two sorted arrays into one sorted array?
  10. [MID] How do you remove duplicates from a sorted and an unsorted array?
  11. [MID] How do you find the missing number in an array containing integers from 1 to n?
  12. [MID] How do you search for an element in a sorted array using binary search?
  13. [SENIOR] What is Kadane's algorithm and how does it find the maximum subarray sum in O(n) time?
  14. [JUNIOR] Why is array element access O(1) and how does contiguous memory allocation enable this?
  15. [JUNIOR] What is a multidimensional array and when would you use one?
  16. [MID] What is the prefix sum technique and how is it used to solve subarray problems?
  17. [MID] How do you reverse an array in-place with O(1) extra space?
  18. [MID] How do you rotate an array by k positions efficiently?
  19. [MID] What are the common sorting algorithms for arrays and what are their time and space complexities?
  20. [SENIOR] How do you search for an element in a rotated sorted array?
  21. [SENIOR] How do you find the majority element in an array that appears more than n/2 times?
  22. [SENIOR] How can you compute the product of all array elements except self without using division?
  23. [SENIOR] How do you find the k-th smallest or largest element in an unsorted array?
  24. [JUNIOR] What is a subarray and how does it differ from a subsequence?
  25. [JUNIOR] What is the difference between shallow copy and deep copy of an array?
  26. [JUNIOR] What is an array index out of bounds exception and how can you prevent it?
  27. [MID] How do you find the largest and smallest elements in an array in a single pass?
  28. [MID] How do you find the second largest element in an array without sorting?
  29. [SENIOR] How do you find the maximum product subarray?
  30. [SENIOR] How do you solve the "Trapping Rain Water" problem using arrays?
  31. [JUNIOR] Why do arrays use 0-based indexing in most programming languages?
  32. [JUNIOR] What is a jagged array and how does it differ from a rectangular multidimensional array?
  33. [MID] How can you find the intersection of two arrays efficiently?
  34. [MID] How do you rearrange an array so that positive and negative numbers alternate?
  35. [SENIOR] How do you find the longest subarray with a given sum?
  36. [SENIOR] How can you efficiently count the number of subarrays with a given sum?
  37. [SENIOR] How do you rotate a matrix by 90 degrees clockwise in-place?
  38. [SENIOR] How do you traverse a matrix in spiral order?
  39. [SENIOR] How do you find the equilibrium index where the left sum equals the right sum in an array?
  40. [EXPERT] How do you merge overlapping intervals in an array of interval pairs?
  41. [EXPERT] How do you solve the 3Sum problem in O(n^2) time?
  42. [JUNIOR] What are sparse arrays and when are they useful?
  43. [MID] What is the difference between row-major and column-major order in memory layout for multidimensional arrays?
  44. [SENIOR] What are inversion counts in an array and how do you calculate them efficiently?
  45. [SENIOR] How do you find the median of two sorted arrays in O(log(min(m,n))) time?
  46. [EXPERT] How do you find the maximum sum of a circular subarray?
  47. [EXPERT] How do you find the first missing positive integer in an unsorted array in O(n) time and O(1) space?
  48. [EXPERT] What is the "Sliding Window Maximum" problem and how do you solve it in O(n) time using a deque?
  49. [EXPERT] How do you solve the "Container With Most Water" problem?
  50. [EXPERT] How do you find the longest increasing subsequence in an array?
  51. [EXPERT] How can you partition an array into two subsets with equal sum?
  52. [EXPERT] How do you find the missing and repeating number in an array of 1 to n using bit manipulation?
  53. [EXPERT] How does cache locality affect array performance compared to pointer-based data structures?