Magento cart price rule

Question

I want to offer 50% offer for the products added in to the cart. It need to working like suppose i have 2 products on my cart A and B. A have $100 and B have $200 suppose i apply the promo code it will reduce the 50% price of the most lesser price product so here $100 reduced as $50. Like i have 3 products it will affect only 1. Suppose i have 4 products it will reduce 2 product price.

Here are the current settings:

Apply = Percent of product price discount
Discount Amount = 25
Discount Qty Step (Buy X) = 0

Answer 1

You can not create this rule only with the native Shopping Cart Promotion Rules of Magento. You can create an extension that will insert a custom condition and/or create a custom field to create a multiplier to determine how many products will be affected by discount. This is a good starting point: https://stackoverflow.com/questions/11864012/shopping-cart-rules-with-custom-condition.

Still, it seems confused how many products will actually be awarded the discount. I believe that changing a bit the way you want to give discount you can reach your target audience effectively.