Problem

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”.

Note:

S and J will consist of letters and have length at most 50.The characters in J are distinct.

Example1

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

Example2

Input: J = “z”, S = “ZZ” Output: 0

Solution

class Solution { public: int numJewelsInStones(string J, string S) { unordered_set<char> hash; for(auto c:J) { hash.insert(c); } int ret = 0; for(auto c:S) { if(hash.count(c)) ++ret; } return ret; } };