Solution: Accounts Merge

Statement

You are given a 2D array, accounts, where each row, accounts[i], is an array of strings, such that the first element, accounts[i][0], is a name, while the remaining elements are emails associated with that account. Your task is to determine if two accounts belong to the same person by checking if both accounts have the same name and at least one common email address.

If two accounts have the same name, they might belong to different people since people can have the same name. However, all accounts that belong to one person will have the same name. This implies that a single person can hold multiple accounts.

The output should be a 2D array in which the first element of each row is the name, and the rest of the elements are the merged list of that user’s email addresses in sorted order. There should be one row for each distinct user, and for each user, each email address should be listed only once.

Note: Please use a sort function that sorts the email addresses based on the ASCII value of each character.

Constraints:

• $1 <=$ accounts.length $<= 100$

• $2 <=$ accounts[i].length $<= 10$

• $1 <=$ accounts[i][j].length $<= 30$

• Because accounts[i][0] is the name of any person, it should contain only English letters.

• For $j>0$, accounts[i][j] should be a valid email.

Solution

We can use the union find pattern to effectively merge the accounts with common emails. We begin by assigning unique IDs to each account, with each ID representing a distinct set. Then, we traverse all the accounts along with their associated emails. During this iteration, each email is mapped to the ID of its corresponding account. If an email is encountered for the second time, indicating it is shared between accounts, we merge the sets using the union method. This step consolidates accounts that share common emails into single entities. After processing all the accounts, we iterate through each merged account and sort the emails within them.

To use the union find pattern, we create and use the UnionFind class, which has two primary methods:

• find(node): Returns the set’s main representative, the root parent, of a given node.

• union(node1, node2): Merges the sets of ...