Position-size-based-on-average-of-cash-remaining

Hello, I would like to ask if it is possible to implement dynamic position setting in building block to achieve this:

All screened stocks are given an average of the remaining cash position in the current account.

Let's say I have 50k cash in my account.

Today my strategy runs out of 10 stocks, so I buy 5k per stock to achieve a full position.

The next day I close half of these positions therefore the account has 25k cash, at this point if 10 stocks were screened out then each stock is allocated an average of 2.5k

Thanks！