README.md

893. Groups of Special-Equivalent Strings

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:

1. Every pair of strings in the group are special equivalent, and;
2. 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.

Solutions (Rust)

1. Count

use std::collections::HashSet;

impl Solution {
    pub fn num_special_equiv_groups(a: Vec<String>) -> i32 {
        let mut set = HashSet::new();

        for s in a {
            let mut cnt = vec![0; 52];
            for (i, c) in s.bytes().enumerate() {
                cnt[(c - b'a') as usize + 26 * (i % 2)] += 1;
            }
            set.insert(cnt);
        }

        set.len() as i32
    }
}