893. Groups of Special-Equivalent Strings.cpp

You are given an array A of strings.

A move onto S consists of swapping any two even indexed characters of S, or any two odd indexed characters of S.

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

For example, S = "zzxy" and T = "xyzz" are special-equivalent because we may make the moves "zzxy" -> "xzzy" -> "xyzz" that swap S[0] and S[2], then S[1] and S[3].

Now, a group of special-equivalent strings from A is a non-empty subset of A such that:

Every pair of strings in the group are special equivalent, and;
The group is the largest size possible (ie., there isn't a string S not in the group such that S is special equivalent to every string in the group)
Return the number of groups of special-equivalent strings from A.


Example 1:

Input: ["abcd","cdab","cbad","xyzz","zzxy","zzyx"]
Output: 3
Explanation:
One group is ["abcd", "cdab", "cbad"], since they are all pairwise special equivalent, and none of the other strings are all pairwise special equivalent to these.

The other two groups are ["xyzz", "zzxy"] and ["zzyx"].  Note that in particular, "zzxy" is not special equivalent to "zzyx".
Example 2:

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


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.





class Solution {
public:
    int numSpecialEquivGroups(vector<string>& A) {
        set<pair<string, string> > s;

        for(auto str: A){
            pair<string, string> p;
            for(int i=0;i<str.length();i++){
                if(i%2==0) p.first+=str[i];
                else p.second+=str[i];
            }
            sort(p.first.begin(), p.first.end());
            sort(p.second.begin(), p.second.end());
            s.insert(p);
        }
        return s.size();
    }
};