jewels-and-stones

Jewels and Stones

LeetCode #: 771

Difficulty: Easy

Topics: Hash Table.

Problem

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.

Complexity Analysis

Time complexity: O(J+S). We processed every character in J and S once.

Space complexity: O(J) with the use of the Set object to store the characters in J.