最長非公共子序列（既不相同也不重複）Longest Uncommon Subsequence II

問題：

Given a list of strings, you need to find the longest uncommon subsequence among them. 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 a list of 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", "eae"
Output: 3

Note:

1. All the given strings' lengths will not exceed 10.
2. The length of the given list will be in the range of [2, 50].

解決：

①  暴力解決。遍歷全部的字符串，對於每一個遍歷到的字符串，再和全部的其餘的字符串比較，看是否是某一個字符串的子序列，若是都不是的話，那麼當前字符串就是一個非共同子序列，用其長度來更新結果res。

class Solution { //11ms
    public int findLUSlength(String[] strs) {
        int res = -1;
        int j = 0;
        int len = strs.length;
        for (int i = 0;i < len;i ++){
            for (j = 0;j < len;j ++){
                if (i == j) continue;
                if (isSubs(strs[i],strs[j])) break;
            }
            if (j == len) res = Math.max(res,strs[i].length());
        }
        return res;
    }
    public boolean isSubs(String subs,String str){
        int i = 0;
        for (char c : str.toCharArray()){
            if (c == subs.charAt(i)) i ++;
            if (i == subs.length()) break;
        }
        return i == subs.length();
    }
}

② 按照字符串長度降序排列strs；遍歷strs，若是str不是全部strs的獨有子字符串，返回str的長度；若是沒有找到獨有字符串，返回-1。

class Solution { //12ms
    public int findLUSlength(String[] strs) {
        Arrays.sort(strs, new Comparator<String>() {//按照長度從大到小排序
            @Override             public int compare(String o1, String o2) {                 return o2.length() - o1.length();             }         });         for (int i = 0;i < strs.length;i ++){             int noMatches = strs.length - 1;             for (int j = 0;j < strs.length;j ++){                 if (i != j && isSub(strs[i],strs[j])){                     noMatches --;                 }                 if (noMatches == 0){                     return strs[i].length();                 }             }         }         return -1;     }     public boolean isSub(String s1,String s2){         int i = 0;         for (char c : s2.toCharArray()){             if (i < s1.length() && s1.charAt(i) == c){                 i ++;             }         }         if (i == s1.length()){             return false;         }         return true;     } }