771_Jewels and Stones

import java.util.HashMap; import java.util.Map; class Solution { public int numJewelsInStones(String jewels, String stones) { Map<Character, Boolean> hashMap = new HashMap<>(); for (char jewel : jewels.toCharArray()) { hashMap.put(jewel, true); } int count = 0; for (char stone : stones.toCharArray()) { if (hashMap.containsKey(stone)) { count++; } } return count; } }