题目要求
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".
Input: J = "aA", S = "aAAbbbb"
Output: 3
S and J will consist of letters and have length at most 50.The characters in J are distinct.
题目分析及思路
题目要求J中的字符都不一样，找出S中与J中字符相同的字符个数。可以用两层循环遍历两个字符串，还可引入集合进行比较。
python代码
class Solution:
def numJewelsInStones(self, J, S):
"""
:type J: str
:type S: str
:rtype: int
"""
jewels = set(J)
sum = 0
for c in S:
if c in jewels:
sum += 1
return sum