# 893. Groups of Special-Equivalent Strings 特殊等价字符串组

@TOC

## # 题目描述

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
``````

Note:

1. 1 <= A.length <= 1000
2. 1 <= A[i].length <= 20
3. All A[i] have the same length.
4. All A[i] consist of only lowercase letters.

## # 解题方法

``````class Solution(object):
def numSpecialEquivGroups(self, A):
"""
:type A: List[str]
:rtype: int
"""
B = set()
for a in A: