Missing test cases

#1

in the way i have taken substrings. if i find a cb number in a string of length lets say 4, i cross the indexes in my valid array. if the substring further consists of 2 or more cb numbers, then i am unable to acces them.

#2

i have modified Your code

and commented the steps i have done
you can check

Modified Code

if you have any problem in this feel free to ask

#3

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