Group anagrams

Link: https://leetcode.com/problems/group-anagrams/

Solution:

Topics: hash map

Intuition
Cute little problem. Not much to it though. Just keep a hash map with the frequency as the value (tuple or sorted string).

Implementation

def group_ana(strs):
	words = {}
	for word in strs:
		freq = [0] * 26
		for char in word:
			freq[ord(char)-ord('a')] += 1
		freq = tuple(freq)
		if freq not in words:
			words[freq] = []
		words[freq].append(word)
	return words.values()
 
#time: o(nk) k = max word length
#memory: o(nk)

Review 1
Sorted string solution is much more elegant and memory efficient…although technically a bit slower in the worst case.

review