0771. Jewels and Stones

https://leetcode.com/problems/jewels-and-stones

Description

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.

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