LeetCode - Jewels and Stones

Question Definition

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.

  Java Solution

  public int numJewelsInStones(String J, String S) {
    Set<Character> set = new HashSet<>();
    for(char c : J.toCharArray())
        set.add(c);
    int result = 0;
    for(char c : S.toCharArray())
        if(set.contains(c)) result++;
    return result;
  }