Strengths:

• The twoSum solution is efficient and correctly implemented using a hash map to achieve O(N) time complexity.
• The code is well-organized and readable, with clear variable names and logical structure.
• The knapsack solutions demonstrate a good understanding of dynamic programming and recursion.

Areas for Improvement:

• The twoSum solution could be slightly optimized by returning the result immediately upon finding the complement, rather than continuing to iterate through the array.
• The knapsack recursive solution could be improved with memoization to avoid redundant calculations and improve performance.
• The main method in Problem1.java is not properly defined (missing String[] args parameter), which would cause a runtime error if executed.