Jewels and Stones

Similar Problems:

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.

Github: code.dennyzhang.com

Credits To: leetcode.com

Leave me comments, if you have better ways to solve.

// https://code.dennyzhang.com/jewels-and-stones // Basic Ideas: set/hashmap // Complexity: Time O(n), Space O(n) func numJewelsInStones(J string, S string) int { m := map[rune]bool{} for _, ch := range J { m[ch] = true } res := 0 for _, ch := range S { if m[ch] == true { res++ } } return res }