leetcode771. Jewels and Stones

You're given strings jewels representing the types of stones that are jewels, and stones representing the stones you have. Each character in stones is a type of stone you have. You want to know how many of the stones you have are also jewels.

Letters are case sensitive, so "a" is considered a different type of stone from "A".

Example 1:

Input: jewels = "aA", stones = "aAAbbbb"Output: 3

Example 2:

Input: jewels = "z", stones = "ZZ"Output: 0

Constraints:

• 1 <= jewels.length, stones.length <= 50

• jewels and stones consist of only English letters.

• All the characters of jewels are unique.

Runtime: 3 ms, faster than 32.45% of Java online submissions for Jewels and Stones.

Memory Usage: 42.7 MB, less than 15.42% of Java online submissions for Jewels and Stones.