[leetcode] 893. Groups of Special-Equivalent Strings

题目：

You are given an array A of strings.

Two strings S and T are special-equivalent if after any number of moves, S == T.

A move consists of choosing two indices i and j with i % 2 == j % 2, and swapping S[i] with S[j].

Now, a group of special-equivalent strings from A is a non-empty subset S of A such that any string not in S is not special-equivalent with any string in S.

Return the number of groups of special-equivalent strings from A.

Example 1:

Input: ["a","b","c","a","c","c"]
Output: 3
Explanation: 3 groups ["a","a"], ["b"], ["c","c","c"]

Example 2:

Input: ["aa","bb","ab","ba"]
Output: 4
Explanation: 4 groups ["aa"], ["bb"], ["ab"], ["ba"]

Example 3:

Input: ["abc","acb","bac","bca","cab","cba"]
Output: 3
Explanation: 3 groups ["abc","cba"], ["acb","bca"], ["bac","cab"]

Example 4:

Input: ["abcd","cdab","adcb","cbad"]
Output: 1
Explanation: 1 group ["abcd","cdab","adcb","cbad"]

Note:

• 1 <= A.length <= 1000
• 1 <= A[i].length <= 20
• All A[i] have the same length.
• All A[i] consist of only lowercase letters.

代码：

class Solution {
    public int numSpecialEquivGroups(String[] A) {
        Set<String> set = new HashSet<>();
        for(String str : A){
            set.add(func(str));
        }
        return set.size();
    }
    
    public String func(String t){
        if(t.length() == 1) return t;
        int[] ch = new int[52];
        for(int i = 0; i < t.length(); i++){
            if(i % 2 == 0) ch[t.charAt(i) - 'a']++;
            else ch[t.charAt(i) - 'a' + 26]++;
        }
        StringBuilder s = new StringBuilder();
        for(int n : ch){
            s.append(n);
        }
        return s.toString();
    }
}