There are ungrouped ones in the answers to the questions I showed in the picture.Bottom one is my solving style but the right answer is upper pic .Shouldn’t we group each one in the map? What is this?
>Solution :
The drawing is a little unclear I think.
If you read the actual answer, you’ll notice that there are two options for the final grouping:
A'BD
or
BCD
BCD is the grouping in red in your answer, while A’BD is the grouping:
So there are two options for grouping that lone 1, and the answer considers both of them. It just doesn’t draw both of them.
The giveaway is that a single cell needs 4 terms to specify it — that 1 on its own would be A'BCD. However there aren’t any elements with 4 terms in the answer, which means that the answer must have grouped it with another cell.