mediumHashingPattern: Hashing
Galaxy Signal Decoding Solution
Problem Statement
In a distant galaxy, signals are transmitted as strings of characters. Given a signal string and a scanner width, find the length of the first segment where all characters are unique. If no such segment exists within the given signal, return -1.
Examples
Example 1:
Input:{"signal":"abcdefghijklmnopqrstuvwxyz","scannerWidth":5}
Output:5
Explanation: The first 5 characters 'abcde' are all unique, so the function returns 5.
Example 2:
Input:{"signal":"abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz","scannerWidth":27}
Output:-1
Explanation: Since the scanner width is 27 and there are only 26 unique characters in the alphabet, no segment of length 27 with all unique characters exists, so the function returns -1.
Constraints
- 1 <= scannerWidth <= 100
- 1 <= signal length <= 1000
- signal consists of lowercase English letters only
Time: O(n) Space: O(min(n, m))
An optimized approach uses a sliding window technique in conjunction with a set to track unique characters within the current window, allowing for a linear time complexity. This method efficiently scans the signal string and identifies the first segment with all unique characters.
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