242. Valid Anagram

#Problem

Given two strings s and t, return true if t is an anagram of s, and false otherwise.

An anagram is a word or phrase formed by rearranging the letters of a different word or phrase, using all the original letters exactly once.

https://leetcode.com/problems/valid-anagram/

Example 1:

Input: s = "anagram", t = "nagaram"
Output: true

Example 2:

Input: s = "rat", t = "car"
Output: false

Constraints:

• 1 <= s.length, t.length <= 5 * 10⁴
• s and t consist of lowercase English letters.

Follow up: What if the inputs contain Unicode characters? How would you adapt your solution to such a case?

#Test Cases

class Solution:
    def isAnagram(self, s: str, t: str) -> bool:

import pytest

from solution import Solution


@pytest.mark.parametrize('s, t, expected', [
    ("anagram", "nagaram", True),
    ("rat", "cat", False),
])
class Test:
    def test_solution(self, s, t, expected):
        sol = Solution()
        assert sol.isAnagram(s, t) == expected

#Thoughts

题目限定了只有小写英文字母，可以用大小为 26 的数组记录每个字母出现的次数。

如果可以包含任意 Unicode 字符，那么用哈希表记录每个字符的次数。

#Code

class Solution:
    def isAnagram(self, s: str, t: str) -> bool:
        counts = [0] * 26
        for c in s:
            counts[ord(c) - 97] += 1

        for c in t:
            counts[ord(c) - 97] -= 1

        return not any(counts)