Description
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:

Both strings' lengths will not exceed 100.
Only letters from a ~ z will appear in input strings.
題目分析
本題要求給出兩個(gè)字符串的最長(zhǎng)不相同序列。若兩個(gè)字符串的長(zhǎng)度和內(nèi)容完全相同，則返回-1。
本題可以通過(guò)字符串比較函數(shù)strcmp來(lái)解決，若兩個(gè)字符串相等，返回-1.若不相等，則較長(zhǎng)的一個(gè)必定與較短的完全不相同，即較長(zhǎng)的為最大不相同序列，返回其長(zhǎng)度即可。
C語(yǔ)言代碼

int findLUSlength(char* a, char* b) {
    int len1=strlen(a);
    int len2=strlen(b);
    int lenmin=len1,lenmax=len2;
    int s=strcmp(a,b);
    if(s==0)             //strcmp==0表示內(nèi)容和長(zhǎng)度均相同。
        return -1;
    else                 //不相同，則最長(zhǎng)的串必定不是最短的串的子序列，因此必定是最長(zhǎng)不同序列。
    {
        if(lenmax<lenmin)
            lenmax=lenmin;
        return lenmax;
    }
        
}

參考文獻(xiàn)
[1] https://leetcode.com/problems/longest-uncommon-subsequence-i/#/description
[2] http://www.bubuko.com/infodetail-2009549.html