leetcode讲解--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.

讲解

这道题我刚开始又没看懂，我以为是数组是一个字符串，对这个数组进行奇偶位的swap。后来终于懂了，是对数组中的每个字符串进行奇偶位的swap。

Java代码

class Solution {
    public int numSpecialEquivGroups(String[] A) {
        Set<List> set = new HashSet<>();
        for(String s:A){
            char[] c = s.toCharArray();
            List<Character> temp1 = new ArrayList<>();
            if(c.length>2){
                List<Character> temp2 = new ArrayList<>();
                for(int i=0;i<c.length;i+=2){
                    temp1.add(c[i]);
                }
                Collections.sort(temp1);
                for(int i=1;i<c.length;i+=2){
                    temp2.add(c[i]);
                }
                Collections.sort(temp2);
                temp1.addAll(temp2);
            }else{
                for(int i=0;i<c.length;i++){
                    temp1.add(c[i]);
                }
            }
            set.add(temp1);
        }
        return set.size();
    }
}