771_Jewels_and_Stones.cpp

class Solution {
public:
    int numJewelsInStones(string J, string S) {
        int res = 0;
        for (int i = 0; i < J.length(); i ++) {
            for (int j = 0; j < S.length(); j ++) {
                if (J[i] == S[j]) {
                    res ++;
                }
            }
        }
        return res;
    }
};