Mrinalini Bansal Thank you for explanation, this is a beautiful solution. I've been studied for this solution for 2 days and finally get the idea. However, I still don't know how to get to this solution from observing optimal substructure. I don't know what is the optimal substructure and also how to get to the recursive function from optimal substructure?

Hi, regarding to problem IV, you mentioned approach 2 For every stock, calculate cash in hand after buying and selling it in the two arrays. This is done in a loop j from 1 till k where j denotes the cash in hand after jth buy and sell. so j is from 1 to k but in code, j is from k to 1? btw, your linkedln is locked and can't send message