Cyclic Character Sequence Validator — Problem Statement & Solution Guide
Problem Description
Given a string sequence, determine if it can be rearranged into a cyclic sequence of characters where 'k' follows 'j', and all other characters follow alphabetically.
Examples
Input
sequence = 'abcba'
Output
True
Explanation: Step-by-step: We can rearrange the sequence 'abcba' into a cyclic sequence where 'c' follows 'b' alphabetically, and 'a' follows 'c' alphabetically. Therefore, the output is True.
Input
sequence = 'abccba'
Output
True
Explanation: Step-by-step: We can rearrange the sequence 'abccba' into a cyclic sequence where 'c' follows 'b' alphabetically, and 'a' follows 'c' alphabetically. Therefore, the output is True.
Constraints
- The input string will only contain lowercase letters.
- The length of the input string will not exceed 500 characters.
Optimal Approach & Strategy
A more efficient approach involves using a data structure such as a linked list or a circular buffer to keep track of the characters and their order in the sequence, allowing for a time complexity of O(n). This approach takes advantage of the fact that the sequence has a specific pattern and can be rearranged efficiently.
Brute Force Approach
A brute-force approach would involve generating all possible permutations of the input string and checking each one to see if it satisfies the pattern, resulting in a time complexity of O(n!). This approach is inefficient and impractical for large inputs. It can be improved by using backtracking to reduce the number of permutations to check.
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