Longest Uncommon Subsequence I

Posted 2020-10-05 白常福

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.

 

分析：寻找最长子序列，要求不能是其他序列的子集。这里需要弄清楚，若两个字符串不完全相等，则最长的那个字符串一定都满足上述条件。所以结果很简单，只用判断字符串是否相等即可。

JAVA CODE

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