Validate string complete
Last updated: December 27, 2025
Quick Overview
Given a string, implement a function to validate whether it is a complete string, meaning that all opening brackets (parentheses, square brackets, and curly braces) have corresponding closing brackets in the correct order. The function should return a boolean value: true if the string is complete and false otherwise. The input will be a single string consisting of characters including brackets, and the output will be a boolean indicating the validation result.
CrowdStrike
December 27, 2025296
14
1,749 solved
Given a string, implement a function to validate whether it is a complete string, meaning that all opening brackets (parentheses, square brackets, and curly braces) have corresponding closing brackets in the correct order. The function should return a boolean value: true if the string is complete and false otherwise. The input will be a single string consisting of characters including brackets, and the output will be a boolean indicating the validation result.
This coding problem is frequently asked during Onsite at CrowdStrike. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. CrowdStrike 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?
- What is the worst-case input for your solution?
- Can you solve this in a single pass?
- What if the input doesn't fit in memory?
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Practice DSA ProblemsSample Answer
Problem Analysis
The problem requires us to validate whether a string containing various types of brackets (parentheses, square brackets, and curly braces) is complete. This can be efficiently solved using the **stack...
Approach
- Initialize an empty stack.
- Create a mapping of closing brackets to their corresponding opening brackets:
{'(': ')', '{': '}', '[': ']'}. - Iterate through each character in the input string: ...
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