← Capital One Interview Insights
Basically just iterate and keep a running sum, return the index when you cross the threshold.
Start by clarifying the problem: confirm the array represents daily visit counts, the target is a positive integer, and we need the first index where the cumulative sum is >= target. Then propose a single-pass solution that maintains a running sum and returns the index as soon as the condition is met, noting O(n) time and O(1) space.
Pro tip: Mention edge cases upfront, such as an empty array or a target that is never reached, and discuss how to handle them (e.g., return -1). This shows attention to detail and defensive coding, which is highly valued at Capital One.
Ask about input size, data types, whether the target can be zero or negative, and what to return if the target is never met. Confirm the expected return type (index or -1).
Explain that you will iterate through the array once, keeping a running sum. At each step, check if the sum meets or exceeds the target; if so, return the current index.
State that the time complexity is O(n) because each element is visited once, and space complexity is O(1) since only a running sum variable is used.
Discuss scenarios like empty array, target <= 0, or target larger than total sum. Decide on return values (e.g., -1 for not found) and ensure they are consistent.
Walk through a small example, such as visits = [10, 20, 30, 40], target = 50, and show that the running sum reaches 60 at index 2, so return 2.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.