Given a non-negative integer represented in the form of a numeric string str. Remove zero or more characters from the string such that the number becomes divisible by 8. If it is possible, print the string after removing the characters otherwise print -1.
Input: str = “3454”
After removing ‘5’, string becomes 344 which is divisible by 8.
Input: str = “111”
Approach: Considering the divisibility rule of 8, we just need to check if the number formed by last 3 characters of str is divisible by 8 or not. Thus, we can iterate over all multiples of 8 upto 1000 and check if any of the multiple exists as a sub-sequence in the given string, then that multiple is our required answer. Otherwise, there exists no answer since all multiples of 8 greater than 1000 also needs to have the number (formed from last 3 digits) which has already been checked.
Below is the implementation of the above approach:
- Remove even frequency characters from the string
- Remove characters from string that appears strictly less than K times
- Count of times second string can be formed from the characters of first string
- Largest sub-string of a binary string divisible by 2
- Permutation of a string with maximum number of characters greater than its adjacent characters
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