mediumStringsPattern: Mixed
Alternating Signal Sequences Solution
Problem Statement
Given a string of signals consisting of 'A', 'B', and 'C', find the length of the longest substring where the signals appear in an alternating sequence of 3 distinct signal types, with each signal type appearing only once in the sequence and the sequence starting and ending with either 'A' or 'C'.
Examples
Example 1:
Input:ABCABC
Output:6
Explanation: The longest substring with alternating sequence of 3 distinct signal types is the entire string
Example 2:
Input:ABABAB
Output:0
Explanation: No substring has all 3 distinct signal types
Constraints
- The input string will only contain the characters 'A', 'B', and 'C'.
- The length of the input string will not exceed 1000 characters.
Time: O(n) Space: O(1)
The optimal approach uses a sliding window technique to efficiently scan the input string, keeping track of the maximum length of the valid alternating sequence found so far. This approach has a time complexity of O(n) and can be implemented using a single loop to iterate over the input string.
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