Find shortest distance in string
Last updated: April 5, 2026
Quick Overview
Given a string consisting of lowercase letters, write a function to find the shortest distance between two specified characters in the string. The function should return the minimum number of characters that need to be traversed to get from the first character to the second, or -1 if either character is not present in the string.
Anduril
April 5, 2026194
11
4,614 solved
Given a string consisting of lowercase letters, write a function to find the shortest distance between two specified characters in the string. The function should return the minimum number of characters that need to be traversed to get from the first character to the second, or -1 if either character is not present in the string.
Anduril uses this problem in the Onsite to evaluate your algorithmic thinking. They expect you to discuss multiple approaches, analyze trade-offs between them, and implement the optimal solution with clean, readable code.
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?
- Can you solve this iteratively instead of recursively (or vice versa)?
- How would you parallelize this solution?
- What is the worst-case input for your solution?
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Problem Analysis
To solve the problem of finding the shortest distance between two specified characters in a string, we can recognize that this is a linear search problem. The optimal approach involves using a single ...
Approach
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Initialize two variables to store the last seen indices of the two specified characters. Set them to -1 initially, indicating that the characters have not been found yet.
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Iterate through the st...
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