I recently completed the Capital One Online Assessment and wanted to share some of the questions that appeared during the test. One thing worth noting is that the OA is proctored. Candidates are required to keep their camera on, share their screen, and enable their microphone throughout the assessment.
Overall, the questions were not extremely difficult from an algorithmic perspective, but they required careful implementation, strong attention to detail, and good time management under a monitored environment.
Question 1: Count Key Changes
Given an array of keyboard inputs such as:
['w', 'W', 'a', 'A', 's', 'S']
Determine how many times the pressed key changes throughout the sequence. Uppercase and lowercase versions of the same letter should be treated as identical keys.
For example, moving from 'w' to 'W' does not count as a change, while moving from 'w' to 'a' counts as one change.
This problem primarily tests array traversal and edge-case handling.
Question 2: Longest Common Prefix Between Two Arrays
You are given two arrays of positive integers, arr1 and arr2.
Choose one number x from arr1 and one number y from arr2. Compute the length of the longest common prefix shared by the decimal representations of x and y.
Return the maximum possible common prefix length among all valid pairs. If no common prefix exists, return 0.
Example:
x = 12345 y = 12399 Longest Common Prefix Length = 3
Although the problem appears straightforward, brute-force comparisons can become inefficient for larger inputs. Common optimizations include using prefix sets or Trie-based approaches.
Question 3: Maximum Expression Value in a Matrix
You are given a non-empty matrix containing:
- Digits (0-9)
- Plus signs (+)
- Minus signs (-)
Find a valid expression within the matrix and return the maximum value obtainable from any valid expression.
This was the most challenging problem in the assessment.
The solution involves a combination of matrix traversal, DFS/backtracking, expression validation, and expression evaluation while maintaining the global maximum result.
Candidates with experience in grid search, recursive exploration, and expression parsing generally have an advantage on this question.
Final Thoughts
The Capital One OA is not necessarily designed to test the most advanced algorithms. Instead, it focuses heavily on implementation quality, problem-solving efficiency, and handling details under time pressure.
Many candidates struggle not because they lack technical knowledge, but because online assessments require quick execution, accurate debugging, and strong time management skills.
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For candidates preparing for Capital One, Amazon, Meta, Google, JPMorgan, Goldman Sachs, and other major technology and finance companies, understanding common OA patterns and practicing under realistic time constraints can make a significant difference in overall performance.
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