839. Similar String Groups | LeetCode Solution Using DSU


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



  • 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.


We made a helper function to know whether the two strings are similar or not. Also a DSU class is there to find the parent and to merge the two groups. If you don't know DSU then please read DSU first and then you will get the solution below.

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