Agoda·Software Engineer·Technical Phone Screen·Intermediate

IntermediatePrefer not to say

Jul 2026

Summary

Interviewed for a software engineer role at Agoda and got a classic array problem that felt straightforward until I started second-guessing myself on edge cases. Pretty standard coding round overall.

Questions Asked (1)

Given an integer array and a target value, find two distinct indices where the elements at those indices sum to the target. Return the indices, or an empty result if no such pair exists.

Algorithms & Data Structures

Author's notes

I jumped straight to the hash map approach without asking about negatives or whether multiple valid answers were possible.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the problem constraints (e.g., input size, whether the array is sorted, if duplicates exist, and if the same element can be used twice). Then propose an optimal solution using a hash map to store seen values and their indices, achieving O(n) time and O(n) space. Walk through the algorithm with a small example, and discuss edge cases and potential optimizations.

Pro tip: Mention that you would first ask about the expected input size and whether the array is sorted, as this determines whether a two-pointer approach (O(n log n) with sorting) or a hash map (O(n)) is more appropriate. Also, explicitly state that you assume exactly one solution exists unless told otherwise, and handle the case where no solution exists by returning an empty result.

1. Clarify Requirements and Constraints

Ask about input size, whether the array is sorted, if there are duplicate values, and if the same element can be used twice. Confirm the expected output format (e.g., return indices in any order, or empty array if no pair).

2. Choose the Optimal Approach

Decide between a hash map (O(n) time, O(n) space) and sorting with two pointers (O(n log n) time, O(1) space). For unsorted arrays, the hash map is generally preferred for its linear time complexity.

3. Explain the Algorithm

Describe the hash map approach: iterate through the array, for each element check if target - element exists in the map. If it does, return the current index and the stored index; otherwise, store the element and its index.

4. Walk Through an Example

Use a small example (e.g., nums = [2, 7, 11, 15], target = 9) to demonstrate how the algorithm finds the pair (indices 0 and 1). This shows understanding and helps catch off-by-one errors.

5. Discuss Edge Cases and Complexity

Cover edge cases: no solution, duplicate values, negative numbers, and large input. State time and space complexity (O(n) time, O(n) space for hash map) and mention that the solution returns an empty result if no pair is found.

Key Points to Mention

Hash map for O(n) time complexity
Handling duplicates and ensuring distinct indices
Returning empty result when no pair exists
Time and space complexity analysis
Alternative two-pointer approach for sorted arrays
Clarifying assumptions about input and output

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.