题目
You’re given strings J representing the types of stones that are jewels, and S representing the stones you have. Each character in S is a type of stone you have. You want to know how many of the stones you have are also jewels.
The letters in J are guaranteed distinct, and all characters in J and S are letters. Letters are case sensitive, so “a” is considered a different type of stone from “A”.
解题思路
遍历S中的每一个字符，判断是否在J中出现，判断的时候吧J转换成Set
代码
class Solution:
def numJewelsInStones(self, J: str, S: str) -> int:
res = 0
for s in S:
if s in set(J):
res += 1
return res
