Find shortest distance in string
Last updated: October 23, 2025
Quick Overview
Given a string, write a function to find the shortest distance between two specified characters. The function should return the minimum number of characters between the two characters, not including the characters themselves. If either character is not present in the string, return -1.
Slack
October 23, 202510
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4,644 solved
Given a string, write a function to find the shortest distance between two specified characters. The function should return the minimum number of characters between the two characters, not including the characters themselves. If either character is not present in the string, return -1.
Coding interviews at Slack focus on problem-solving approach as much as the final solution. The interviewer wants to see you break down the problem, consider edge cases, and optimize iteratively. Communication throughout the process is key.
What the Interviewer Expects
- Identify the correct data structure and algorithm for the problem
- Write clean, bug-free code with proper variable naming
- Analyze time and space complexity correctly
- Handle basic edge cases (empty input, single element)
- Communicate your thought process while coding
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 you test this solution thoroughly?
- Can you solve this in a single pass?
- How would you modify your solution to handle streaming input?
- Can you solve this iteratively instead of recursively (or vice versa)?
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Problem Analysis
To find the shortest distance between two specified characters in a string, we can use the two pointers technique. This approach is suitable because we need to track the positions of the two chara...
Approach
- Initialize two variables to store the last seen indices of the two characters, say
last_char_aandlast_char_b, both set to -1 initially. These will help in tracking the positions of the charac...
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