About this solution: This is a great solution! The candidate has taken the time to include comments explaining what the code is doing, which is always appreciated. The code itself is clean and well-organized.

About this solution: The candidate's solution correctly solves the problem and uses a dynamic programming approach. The code is well-written and easy to follow.

About this solution: The candidate's solution correctly finds the maximum average value of a given array and length k. The solution is clear and easy to follow. One potential improvement would be to use the built-in max() and sum() functions rather than creating a custom max_sum function.

About this solution: The candidate's solution correctly finds the first non-repeating character in a string. The solution uses a hash map to keep track of the number of times each character appears in the string, then loops through the string again to find the first character with a count of 1. One potential improvement to this solution would be to use a LinkedHashMap instead of a regular hash map. This would allow the characters to be iterated over in the order in which they appear in the string, which would make the second loop unnecessary.

About this solution: The candidate's solution correctly implements a recursive solution to check if a binary tree is symmetric. The approach is sound, and the code is clean and easy to follow.

About this solution: The candidate's solution is correct and uses a stack to keep track of the order of the brackets. The solution is also complete, with tests for all the different cases.

About this solution: This is a good solution that demonstrates a level of completeness and solves the problem. The approach is straightforward and easy to understand.

About this solution: The candidate's solution is correct and solves the problem. The approach is good, iterating through the array once and keeping track of the sum of the previous k elements. The time complexity is O(n) and the space complexity is O(1).