Jewels and Stones

Description

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.

code:

class Solution {
    public int numJewelsInStones(String J, String S) {
        Map<Character, Integer> map = new HashMap<>();
        char[] s = S.toCharArray();
        for (int i = 0; i < s.length; i++) {
            map.put(s[i], map.getOrDefault(s[i], 0) + 1);
        }
        int count = 0;
        char[] j = J.toCharArray();
        for (int i = 0; i < j.length; i++) {
            if (map.containsKey(j[i])) {
                count += map.get(j[i]);
            }
        }
        return count;
    }
}