Print anagrams together in Python using List and Dictionary

Given an array of words, print all anagrams together. 

Examples:

Input: arr = [‘cat’, ‘dog’, ‘tac’, ‘god’, ‘act’]

Output: ‘cat tac act dog god’

This problem has existing solution please refer Anagrams and Given a sequence of words, print all anagrams together links. We will solve this problem in python using List and Dictionary data structures. Approach is very simple :

• Traverse list of strings.
• Sort each string in ascending order and consider this sorted value as Key and original value as Value of corresponding key. Check if key is not present in dictionary that means it is occurring first time, so map a empty list to Key and append value in it, if key is already present then simple append the value.
• Now each key will contain list of strings which are anagram together.

Implementation:

Python3

# Function to return all anagrams together
def allAnagram(input):

    # empty dictionary which holds subsets
    # of all anagrams together
    dict = {}

    # traverse list of strings
    for strVal in input:

        # sorted(iterable) method accepts any
        # iterable and returns list of items
        # in ascending order
        key = ''.join(sorted(strVal))

        # now check if key exist in dictionary
        # or not. If yes then simply append the
        # strVal into the list of it's corresponding
        # key. If not then map empty list onto
        # key and then start appending values
        if key in dict.keys():
            dict[key].append(strVal)
        else:
            dict[key] = []
            dict[key].append(strVal)

    # traverse dictionary and concatenate values
    # of keys together
    output = ""
    for key,value in dict.items():
        output = output + ' '.join(value) + ' '

    return output

# Driver function
if __name__ == "__main__":
    input=['cat', 'dog', 'tac', 'god', 'act']
    print (allAnagram(input))

Output

cat tac act dog god 

Time Complexity: O(n), where n is the total number of the characters in the given input.
Auxiliary Space: O(n)