题解 | 宝石计数

#
# 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
#
# 
# @param jewels string字符串 
# @param stones string字符串 
# @return int整型
#
class Solution:
    def numJewelsInStones(self , jewels: str, stones: str) -> int:
        # write code here
        seen=set()
        for char in jewels:
            seen.add(char)
        count=0
        for char in stones:
            if char in seen:
                count+=1
        return count