[LeetCode] Longest Uncommon Subsequence I

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.

最长的非共同子序列。题本身不难，但是题目很难读懂。要求两个字符串中的最长非共同子序列，有3种情况：(1) a,b相同，则它们没有非共同子序列，返回-1。(2) a,b不同，但长度相同，则最长非共同子序列就是它们本身，返回a,b的长度。(3) a,b长度不同，则它们最长非共同子序列为长度长的那一个，返回a,b中较长的长度。

class Solution {
public:
    int findLUSlength(string a, string b) {
        if (a == b)
            return -1;
        else
            return max(a.size(), b.size());
    }
};
// 3 ms