We use a hash map where the key is the sorted version of a string (or a character frequency tuple). All anagrams will have the same key.

1. Initialize a hash map ans = defaultdict(list).
2. For each string s in strs:
   • Create a key: sorted_s = "".join(sorted(s)).
   • Append s to ans[sorted_s].
3. Return ans.values().

• Time Complexity: O(N * K log K), where K is the max length of a string.
• Space Complexity: O(N * K).

from collections import defaultdict

def group_anagrams(strs):
    ans = defaultdict(list)
    for s in strs:
        key = "".join(sorted(s))
        ans[key].append(s)
    return list(ans.values())