Given a string input_string, determine the maximum length of any contiguous substring in input_string that contains only unique characters (no character repeats within the substring). Return this maximum length as an integer.
Example 1
Input: "xyzxyzz"
Output: 3
Explanation: The longest substring with unique characters is xyz or yzx, length 3.
Example 2
Input: "aaaa"
Output: 1
Explanation: The longest substring with unique characters is a, length 1.
Example 3
Input: "123456123"
Output: 6
Explanation: The longest substring with unique characters is 123456, length 6.
Constraints
Case 1
Input: "abcbdeaf"
Expected: 5
Case 2
Input: ""
Expected: 0
Case 3
Input: "a b c d e f"
Expected: 7
Case 4
Input: "xyxxyx"
Expected: 2
Case 5
Input: "!@#$$%^&*()"
Expected: 8