For this problem, I accidentally used Java assuming c# and since both syntaxes are almost similar and to my use I haven't used any implicit functions, the code worked

Just look at the runtimes differences. The solution was same for both c# and Java.

Problem:
https://leetcode.com/problems/deepest-leaves-sum/

The solution I did:
https://leetcode.com/problems/deepest-leaves-sum/discuss/2040524/C-Recursion-based-approach