Validate string sorted
Last updated: October 8, 2025
Quick Overview
Given a string, determine if the characters in the string are sorted in non-decreasing order. The function should return a boolean value: true if the string is sorted, and false otherwise. Consider an empty string or a string with a single character as sorted.
Jane Street
October 8, 202510
10
3,396 solved
Given a string, determine if the characters in the string are sorted in non-decreasing order. The function should return a boolean value: true if the string is sorted, and false otherwise. Consider an empty string or a string with a single character as sorted.
This coding problem is frequently asked during Take-home Project at Jane Street. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. Jane Street expects candidates to write production-quality code, not just solve the puzzle.
What the Interviewer Expects
- Quickly identify the optimal approach and its theoretical basis
- Handle complex algorithm design with multiple interacting components
- Write concise, elegant code under time pressure
- Prove correctness of your approach and discuss alternative solutions
- Optimize beyond the obvious: discuss constant factor improvements
- Address follow-up variations and explain how the solution generalizes
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?
- How would you modify your solution to handle streaming input?
- What is the worst-case input for your solution?
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Practice DSA ProblemsSample Answer
Problem Analysis
The problem is to determine if the characters in a given string are sorted in non-decreasing order. This can be efficiently solved using a single pass approach, leveraging a linear scan techni...
Approach
- If the string is empty or has a single character, return
Trueas it is trivially sorted. - Iterate through the string from the first character to the second to last character.
- For each charac...
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