Validate string sorted
Last updated: March 15, 2026
Quick Overview
Given a string, write a function to determine if the characters in the string are sorted in non-decreasing order. The function should return `true` if the string is sorted and `false` otherwise. For example, the input "abc" should return `true`, while "cba" should return `false`.
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March 15, 20263
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Given a string, write a function to determine if the characters in the string are sorted in non-decreasing order. The function should return `true` if the string is sorted and `false` otherwise. For example, the input "abc" should return `true`, while "cba" should return `false`.
Coding interviews at Instacart 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
- Can you optimize the space complexity of your solution?
- How would you parallelize this solution?
- How would you modify your solution to handle streaming input?
- How would your solution change if the input was sorted?
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Problem Analysis
To determine if the characters in the string are sorted in non-decreasing order, we can utilize a simple linear scan approach. This problem can be solved using a two-pointer technique where we ite...
Approach
- Initialize a loop starting from the first character of the string and go until the second to last character.
- In each iteration, compare the current character with the next character.
- If the c...
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