Count duplicate values in Excel

Question

I have a column filled with 0s and 1s like this:

A

1
1
1
0
0
1
0
1
1
0
0
1
0
0
1

What I want to do is simply have another column, with this values being counted until the next limit, like this:

A    B

1    1
1    2
1    3
0    1
0    2
1    1
0    1
1    1
1    2
0    1
0    2
1    1
0    1
0    2
1    1

I have searched for an answer, but I only found old posts and formulas that didn't work. This should be a simple thing. I only want one formula and I prefer to use only one column! I'm a noobie in Excel formulas.

Things I've tried but didn't work:

1. Count duplicate values in a sequence
2. Counting duplicates in Excel
3. How do I count consecutive same values
4. And other sources.

Answer 1

steps as below

1. write cell B1 with 1
2. write cell B2 with =IF(A2=A1,B1+1,1)
3. drag cell B2 down