Groups Of Strings - Leetcode Solution

Problem Statement:

Given an array of strings strs, group the anagrams together. You can return the answer in any order.

An Anagram is a word or phrase formed by rearranging the letters of a different word or phrase, typically using all the original letters exactly once.

Example 1:

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

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

Example 2:

Input: strs = [""]

Output: [[""]]

Example 3:

Input: strs = ["a"]

Output: [["a"]]

Constraints:

1 <= strs.length <= 104

0 <= strs[i].length <= 100

strs[i] consists of lowercase English letters.

Approach:

The problem can be solved using the hashmap data structure in order to group the anagrams together.

1. Define a hash map. The key of the map will be sorted string and value will be list of anagram words.

2. Loop through the strings in the given input list “strs”

3. Sort each string and group strings with the same sorted string in a list

4. Return the list of lists.

Algorithm:

1. Create a data structure a hashmap, where the key will be the sorted form of each word in array and value will be a list of strings.

2. Loop through the strings in the given input list "strs".

3. Sort each string and group its anagrams together by appending it to same list in hashmap.

4. Loop through the keys of hashmap and store the string values in a separate list.

5. Return this list.

Pseudo-code:

def groupAnagrams(strs: List[str]) -> List[List[str]]: anagramGroups = {}

# Loop through each string in strs list
for s in strs:
    
    # Sort the string and store a key in the map
    sortedString = ''.join(sorted(s))
    
    # Append the original string to the list
    if sortedString in anagramGroups:
        anagramGroups[sortedString].append(s)
    else:
        anagramGroups[sortedString] = [s]

# Return the list of anagram groups
return list(anagramGroups.values())

Code:

class Solution(object): def groupAnagrams(self, strs): """ :type strs: List[str] :rtype: List[List[str]] """ anagramGroups = {}

    # Loop through each string in strs list
    for s in strs:
        
        # Sort the string and store a key in the map
        sortedString = ''.join(sorted(s))
        
        # Append the original string to the list
        if sortedString in anagramGroups:
            anagramGroups[sortedString].append(s)
        else:
            anagramGroups[sortedString] = [s]
    
    # Return the list of anagram groups
    return list(anagramGroups.values())

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