I have the following table:

A B
0 W
1 W
0 D
0 W
0 D
1 W
0 W
1 D

Is there a way to count or sum up a series of text or number within a
column? E.g.
i) count the number of times the alphabet W appears in sequence of 2 times
(i.e. B2 and B3 in a column)? Table above shows W appearing twice in sequence.
ii) count the number of times the number zero (0) appears in a sequence of 3
times within a column?

Appreciate any help, thanks!