Checking if two strings are permutations of each other

Question

How to determine if two strings are permutations of each other

Answer 1

1. Sort the 2 strings by characters and compare if they're the same (O(n log n) time, O(n) space), or
2. Tally the character frequency of the 2 strings and compare if they're the same (O(n) time, O(n) space).