839 - Similar String Groups.

Hard

Two strings X and Y are similar if we can swap two letters (in different positions) of X, so that it equals Y. Also two strings X and Y are similar if they are equal.

For example, "tars" and "rats" are similar (swapping at positions 0 and 2), and "rats" and "arts" are similar, but "star" is not similar to "tars", "rats", or "arts".

Together, these form two connected groups by similarity: {"tars", "rats", "arts"} and {"star"}. Notice that "tars" and "arts" are in the same group even though they are not similar. Formally, each group is such that a word is in the group if and only if it is similar to at least one other word in the group.

We are given a list strs of strings where every string in strs is an anagram of every other string in strs. How many groups are there?

Example 1:

Input: strs = "tars","rats","arts","star"

Output: 2

Example 2:

Input: strs = "omv","ovm"

Output: 1

Constraints:

• 1 <= strs.length <= 300

• 1 <= strs[i].length <= 300

• strs[i] consists of lowercase letters only.

• All words in strs have the same length and are anagrams of each other.