Transform array to hash map
Last updated: January 30, 2026
Quick Overview
Given an array of key-value pairs, transform it into a hash map where each key is unique and maps to its corresponding value. The input will be an array of strings formatted as "key:value", and the output should be a hash map (or dictionary) that represents these key-value pairs. Handle cases where duplicate keys are present by retaining the last value associated with each key.
Apple
January 30, 202643
5
3,016 solved
Given an array of key-value pairs, transform it into a hash map where each key is unique and maps to its corresponding value. The input will be an array of strings formatted as "key:value", and the output should be a hash map (or dictionary) that represents these key-value pairs. Handle cases where duplicate keys are present by retaining the last value associated with each key.
This coding problem is frequently asked during Onsite at Apple. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. Apple expects candidates to write production-quality code, not just solve the puzzle.
What the Interviewer Expects
- Recognize the underlying problem pattern (sliding window, two pointers, BFS/DFS, etc.)
- Discuss multiple approaches and trade-offs before coding
- Implement an optimal solution with clean, production-quality code
- Handle all edge cases including boundary conditions and invalid input
- Optimize both time and space complexity with clear justification
- Test your solution systematically with well-chosen examples
Key Topics to Cover
How to Approach This
- Clarify input constraints and edge cases before writing code.
- Walk through your approach verbally and confirm with the interviewer before coding.
- Start with a brute force solution, then optimize. Mention time and space complexity.
- Test your solution with examples, including edge cases like empty input or duplicates.
- Consider common patterns: sliding window, two pointers, hash map, BFS/DFS, dynamic programming.
Possible Follow-up Questions
- How would your solution change if the input was sorted?
- What if the input doesn't fit in memory?
- How would you modify your solution to handle streaming input?
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Problem Analysis
The problem requires transforming an array of strings formatted as 'key:value' into a hash map (or dictionary) where keys are unique. The presence of duplicate keys means we need to ensure that the la...
Approach
- Initialize an empty dictionary to hold the key-value pairs.
- Iterate through each string in the input array:
- Split the string by the ':' delimiter to separate the key and value.
- Strip a...
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