I'm taking the udemy course called complete python bootcamp from zero to hero in python.

One of the practice problems is to write a function that given three integers between 1 and 11, if their sum is less than or equal to 21, return their sum. If their sum exceeds 21 and there's an eleven, reduce the total sum by 10. Finally if the sum (even after adjustment) exceeds 21, return "BUST".

def blackjack(a,b,c):

...: if sum([a,b,c]) <= 21:

...: return sum([a,b,c])

...: elif 11 in [a,b,c] and sum([a,b,c]) <=31:

...: return sum([a,b,c])-10

...: else:

...: return "BUST"

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However, for some reason I can't for the life of me understand the less than or equal to 31 part. They give example inputs of (5,6,7), (9,9,9) and (9,9,11), which result in 18, "bust" and 19 respectively.

why not just write if 11 is in the input and sum is greater than 21?

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Are they assuming a max of one ace per hand?

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Also, I tried inputting (11,11,10) which returns "bust". I'm no blackjack expert but wouldn't that hand be a soft 12? So couldnt i do <=32 to account for two 11's?

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I'm probably overthinking this but its still bugging the F outta me.