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Group Anagrams from a List of Strings

Certification: Intermediate Level Accuracy: 100% Submissions: 1 Points: 15

Write a Python function to group anagrams from a list of strings. An anagram is a word or phrase formed by rearranging the letters of a different word or phrase, using all the original letters exactly once. Return a list of lists, where each inner list contains a group of anagrams.

Algorithm for group_anagrams(strs)
  1. Create a dictionary to store anagram groups, where the key uniquely identifies the anagram pattern.
  2. Iterate through each string in the input list.
  3. For each string, generate a key that uniquely identifies its anagram group.
  4. Add the string to the appropriate anagram group in the dictionary.
  5. Return the values of the dictionary as a list of lists.
Example 1
    

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

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

  • Explanation: 

      

    • - "eat", "tea", and "ate" are anagrams of each other.
      • 

    • - "tan" and "nat" are anagrams of each other.
      • 

    • - "bat" has no anagrams in the list.
      • 

    

    •
Example 2
    

  • Input: [""]
    • 

  • Output: [[""]]
    • 

  • Explanation: 

      

    • - There is only one string in the input, which is the empty string.
      • 

    • - The empty string is grouped by itself.
      • 

    

    •
Constraints
    

  • 1 <= strs.length <= 10^4
    • 

  • 0 <= strs[i].length <= 100
    • 

  • strs[i] consists of lowercase English letters
    • 

  • Time Complexity: O(n * k) where n is the number of strings and k is the maximum length of a string
    • 

  • Space Complexity: O(n * k)
    •
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Hint
Solution

Solution Hints

    
  
  • Consider using a hash table to group anagrams
    • 
  
  • Create a key for each string that uniquely identifies its anagram group
    • 
  
  • One approach is to sort each string to use as the key
    • 
  
  • Another approach is to create a count of characters in each string to use as the key
    • 
  
  • Group strings with the same key together in the hash table
    •

Steps to solve by this approach:

 Step 1: Create an empty dictionary to store anagram groups.
 Step 2: Iterate through each string in the input list.
 Step 3: Sort the characters of the current string to create a unique key for its anagram group.
 Step 4: Add the string to the appropriate anagram group in the dictionary based on its key.
 Step 5: Convert the dictionary values (anagram groups) to a list of lists and return the result.

Submitted Code :