題目描述 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”. Example 1:

Input: J = “aA”, S = “aAAbbbb” Output: 3 Example 2:

Input: J = “z”, S = “ZZ” Output: 0 Note:

S and J will consist of letters and have length at most 50. The characters in J are distinct. 解題思路 map(function,iterable)會根據提供的函式對指定序列做對映。 count（）：計數函式

class Solution:
    def numJewelsInStones(self, J, S):
        """
        :type J: str
        :type S: str
        :rtype: int
        """
        return sum(map(S.count, J))