Leetcode 242. 有效的字母异位词 Valid Anagram - Python 哈希法

class Solution:
    def isAnagram(self, s: str, t: str) -> bool:
        record = [0] *26
        for i in s:
#    用哈希法（ 哈希函数：ord(i)-ord('a') ）将'a'映射为0 'b'映射为1..'z'映射为25 其它字母同理
            record[ord(i)-ord('a')] += 1  #此处不用记住ASCII 用ord()计算即可
        for i in t:
            record[ord(i)-ord('a')] -= 1
        for i in range(len(record)):
            if record[i] != 0: #若record有一个字母（元素）不为0 则不是Anagram
                return False
        return True

注：此题也可用defaultdict来做

class Solution:
    def isAnagram(self, s: str, t: str) -> bool:
        from collections import defaultdict
        
        s_dict = defaultdict(int)
        t_dict = defaultdict(int)

        for x in s:
            s_dict[x] += 1
        
        for x in t:
            t_dict[x] += 1

        return s_dict == t_dict