Leetcode Longest Uncommon Subsequence I

原题链接在这里：https://leetcode.com/problems/longest-uncommon-subsequence-i/#/description

题目：

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 any subsequence 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.

Example 1:

Input: "aba", "cdc"
Output: 3
Explanation: The longest uncommon subsequence is "aba" (or "cdc"), 
because "aba" is a subsequence of "aba", 
but not a subsequence of any other strings in the group of two strings. 

Note:

1. Both strings' lengths will not exceed 100.
2. Only letters from a ~ z will appear in input strings.

题解：

两种情况，如果a == b, 那么就没有 uncommon subsequence, return -1.

a != b 那么就是 a, b中较长string为substring. 因为较长的string 不可能是较短string的substring.

Time Complexity: O(Math.min(a.length(), b.length())). 比较a, b是否相等用较短string长度时间.

Space: O(1).

AC Java:

 public class Solution {
     public int findLUSlength(String a, String b) {
         if(a.equals(b)){
             return -1;
         }
         return Math.max(a.length(), b.length());
     }
 }

跟上Longest Uncommon Subsequence II.