I am unable to find out why binary search wont work with this problem Apartments. My Solution using BS:Solution

I have been trying this question 1895C - Порванный счастливый билет and my approach seems to be somewhat aligned with the tutorial but i m not getting AC due to some error in my code 241201430 .Please tell me where i got wrong with the solution.

Can someone please help me out with the solution of this problem "Natsya decided to visit a local store, which has n items. The i-th item has price a[i]

She has to buy k items out of the n items such that total price of all the items bought is minimum.

In how ways she can buy k items such that the overall price is minimum?"

1<=k<=n<=50 a[i]<=n

I have tried to solve it but it is failing in some hidden cases Code.

I have been stuck on the problem and this is best solution i could think and it has failed Question:String Generator My Solution:Based on two pointers checking right and left Please help me and where my solution was wrong and how can it be improved as i havent found an answer to the problem...

I need help in solving a question Question A ,also i tried too hard to understand how to do it from video but couldnt understand it properly...