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Learning strings is a neverending story: predict the next characters in a sequence and look under the hood of strings joining.

💡TIP

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🏁MISSION

Sequence Analyzer by freeman_lex -

Consider a sequence of uppercase alphabetic characters (A-Z). The sequence is said to have a "constant step" if the distance between adjacent characters in the sequence is the same. For example, the distance between A and B is 1, D and F is 2, P and V is 6, Z and C is 3 etc. Two or mor sequences are said to be "intertwined" if their adjacent elements are separated by exactly one element of each of the other sequences.

For the given string of 12 characters of 1, 2 or 3 (find out it by yourself) intertwined sequences, return the next 12 character of the sequence.

analyzer("ACEGIKMOQSUW") == "YACEGIKMOQSU"
analyzer("AQBRCSDTEUFV") == "GWHXIYJZKALB"
analyzer("AZTAYRAXPAWN") == "AVLAUJATHASF"

📖ARTICLE

Joining Strings in Python: why str.join() doesn’t like generators. - In the article you may read about comparison and behavior of generators and lists in a task of joining strings.

👩‍💻CODE SHOT

How do you think, what the following code does?

from itertools import groupby

def ?????????(digits: str) -> str:
    
    return "".join(str(len(list(counter))) + current
                   for current, counter in groupby(digits))

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