completed competitive coding 3

[abhayb94]

No description provided.

[super30admin]

• Problem1.java: The solution is excellent. The approach is clear, and the implementation is correct. No improvements are needed.
• Problem2.java: The solution is mostly correct, but there is a minor issue with the initial check for k < 0. Instead of returning -1, it should return 0, as no pairs can exist with a negative k. Additionally, the use of a HashSet of Lists is correct but could be optimized further by using a HashSet of Strings or a custom Pair class to reduce overhead.