Jewels and Stones

 

Jewels and Stones

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.

 

 

class Solution {
public:
    int numJewelsInStones(string J, string S) {
        unordered_map<char,int> mp;
        for(int i=0;i<S.size();++i)
            mp[S[i]]++;
        int ans=0;
          for(int i=0;i<J.size();++i)
            if(mp[J[i]])
                ans+=mp[J[i]];
        return ans;
    }
};