LeetCode 521 Longest Uncommon Subsequence I 解题报告

Posted 2021-11-25 yao1996

题目要求

Given a group of two strings, you need to find the longest uncommon subsequence of this group of two strings. The longest uncommon subsequence is defined as the longest subsequence of one of these strings and this subsequence should not be anysubsequence of the other strings.

A subsequence is a sequence that can be derived from one sequence by deleting some characters without changing the order of the remaining elements. Trivially, any string is a subsequence of itself and an empty string is a subsequence of any string.

The input will be two strings, and the output needs to be the length of the longest uncommon subsequence. If the longest uncommon subsequence doesn‘t exist, return -1.

题目分析及思路

给定两个字符串，要求找到最长的uncommon子串，并返回该子串的长度；若不存在就返回-1。最长的uncommon子串定义为：该子串是给定的两个字符串中某一个的最长子串，同时又不是另一个字符串的子串。我们可以考虑两种情况：一是这两个字符串相等，则不存在这样的uncommon子串，所以返回-1；二是这两个字符串不相等，则较长字符串本身就是这个最长的uncommon子串，所以返回它的长度。

python代码

class Solution:

    def findLUSlength(self, a: str, b: str) -> int:

        if a == b:

            return -1

        else:

            return max(len(a), len(b))