771. 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.

Solution

class Solution {
    public int numJewelsInStones(String J, String S) {
        int[] arr = new int[123];
        char[] sarr = S.toCharArray();
        char[] jarr = J.toCharArray();
        for(char c : sarr){
            arr[c]++;
        }
        int k = 0;
        for(char c : jarr){
            k += arr[c];
        }
        return k;
    }
}