2025-08-21

242. Valid Anagram

Question

Check if s and t are anagrams

First solution

• Create {character: count} dict for both strings and compare

O(n), O(n) Iterate through both. Iterate for searching. Store both strings as lists

dict_s = {}
dict_t = {}
for i in s:
	if i not in dict_s:
		dict_s[i] = 1
	else:
		dict_s[i] += 1

for i in t:
	if i not in dict_t:
		dict_t[i] = 1
	else:
		dict_t[i] += 1

return (dict_s == dict_t)

Other ideas

• Sort and compare
  • Time of O(nlogn) but constant space

Neetcode answer

• Create two constant space dict for the form {a:count} where a is the characters of the alphabet
• Then just iterate the strings and populate the dicts
• compare dicts