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This is a easy difficulty Coding & Algorithms question, commonly asked during Onsite rounds at J.P. Morgan.

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Group strings that are anagrams | J.P. Morgan Coding Question

Group strings that are anagrams

Company: J.P. Morgan

Role: Software Engineer

Category: Coding & Algorithms

Difficulty: easy

Interview Round: Onsite

## Problem: Group anagrams Given an array of strings `strs`, group the strings that are anagrams of each other. Two strings are anagrams if they contain the same characters with the same multiplicities (order may differ). ### Input - `strs`: array of strings (assume lowercase English letters unless stated otherwise). ### Output Return a list of groups, where each group is a list of strings that are mutual anagrams. - The order of groups does not matter. - The order of strings inside a group does not matter. ### Constraints (typical) - `1 ≤ len(strs) ≤ 1e5` - `0 ≤ len(strs[i]) ≤ 100` ### Follow-ups discussed in interview - Provide **multiple approaches**, and compare time/space tradeoffs (e.g., sorting-based key vs. character-count key).

Quick Answer: This question evaluates skills in string manipulation, grouping by character composition, and the use of hashing or sorting techniques to construct keys while reasoning about time and space trade-offs.

Given an array of strings `strs`, group the strings that are anagrams of each other. Two strings are anagrams if they contain exactly the same characters with the same frequencies, but possibly in a different order. Return a list of groups, where each group contains strings that are mutual anagrams. For deterministic evaluation in this problem, follow these output-order rules: 1. Groups must appear in the order their anagram class is first seen in the input. 2. Strings inside each group must remain in their original input order. Example: `['eat', 'tea', 'tan', 'ate']` should become `[['eat', 'tea', 'ate'], ['tan']]`.

Constraints

0 <= len(strs) <= 100000
0 <= len(strs[i]) <= 100
Each string contains only lowercase English letters 'a' to 'z'

Examples

Input: (["eat", "tea", "tan", "ate", "nat", "bat"],)

Expected Output: [["eat", "tea", "ate"], ["tan", "nat"], ["bat"]]

Explanation: "eat", "tea", and "ate" are anagrams; "tan" and "nat" are anagrams; "bat" stands alone.

Input: (["", "b", ""],)

Expected Output: [["", ""], ["b"]]

Explanation: Both empty strings belong to the same group, and that group appears first because the first element is an empty string.

Input: ([],)

Expected Output: []

Explanation: An empty input list produces no groups.

Input: (["ab", "ba", "ab", "cd", "dc", "e"],)

Expected Output: [["ab", "ba", "ab"], ["cd", "dc"], ["e"]]

Explanation: Duplicate strings are allowed and remain in the same anagram group in their original order.

Input: (["abc"],)

Expected Output: [["abc"]]

Explanation: A single string forms a group by itself.

Hints

You need a way to map every string to an anagram signature so that all anagrams produce the same key.
A sorted version of the string works as a key, but with lowercase letters only, a 26-character frequency count can be even more efficient.

Quick Overview

This question evaluates skills in string manipulation, grouping by character composition, and the use of hashing or sorting techniques to construct keys while reasoning about time and space trade-offs.