No need for "{0:b}", "{:b}" will work also.

Yes

I'm still learning time complexity, this is O(n^2) right?

Clever kind but impractical

f'Maybe you\'d want to try new {string_formatting} that has been available since Python 3.6'

format function,got it

The only solution that makes some sense here!

Note: above comment is true only for python 3 & not for python 2.

Use spoiler flag next time.

Read the descriptions carefully:

return the first two values (parse from the left please) in order of appearance that add up to form the sum

You're not always returning the pairs in order.