動機

如果有機會面試，我就出這題

Problem

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 "aebdc" to get "abc". Other subsequences of "aebdc" include "aebdc", "aeb", and "" (empty string).

 

Example 1:

Input: a = "aba", b = "cdc"Output: 3Explanation: 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: 3Explanation: The longest uncommon subsequences are "aaa" and "bbb".

Example 3:

Input: a = "aaa", b = "aaa"Output: -1Explanation: 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.

Sol

Longest Uncommon Subsequence的重點是最長一定是單字本身

class Solution:
    def findLUSlength(self, a: str, b: str) -> int:
        if a == b:
            return -1
        else:
            return max(len(a),len(b))