題目：
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"
- python
def numJewelsInStones(self, J, S):
setJ = set(J)
return sum(s in setJ for s in S)
- 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;
}
