771. Jewels and Stones

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"

1. python

def numJewelsInStones(self, J, S):
        setJ = set(J)
        return sum(s in setJ for s in S)

2. C++

int numJewelsInStones(string J, string S) {
        int res = 0;
        unordered_set<char> setJ(J.begin(),J.end());
        for ( char s:S) if (setJ.count(s)) res++;
        return res;

}