521 - Longest Uncommon Subsequence I.

Easy

Given two strings a and b, return the length of the longest uncommon subsequence between a and b. If the longest uncommon subsequence does not exist, return -1.

An uncommon subsequence between two strings is a string that is a subsequence of one but not the other.

A subsequence of a string s is a string that can be obtained after deleting any number of characters from s.

• For example, "abc" is a subsequence of "aebdc" because you can delete the underlined characters in <code>"a<ins>e</ins>b<ins>d</ins>c"</code> to get "abc". Other subsequences of "aebdc" include "aebdc", "aeb", and "" (empty string).

Example 1:

Input: a = "aba", b = "cdc"

Output: 3

Explanation: One longest uncommon subsequence is "aba" because "aba" is a subsequence of "aba" but not "cdc". Note that "cdc" is also a longest uncommon subsequence.

Example 2:

Input: a = "aaa", b = "bbb"

Output: 3

Explanation: The longest uncommon subsequences are "aaa" and "bbb".

Example 3:

Input: a = "aaa", b = "aaa"

Output: -1

Explanation: Every subsequence of string a is also a subsequence of string b. Similarly, every subsequence of string b is also a subsequence of string a.

Constraints:

• 1 <= a.length, b.length <= 100

• a and b consist of lower-case English letters.