jewelsAndStones.js

// Jewels and Stones

// 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.

//https://leetcode.com/explore/challenge/card/may-leetcoding-challenge/534/week-1-may-1st-may-7th/3317/

/**
 * @param {string} J
 * @param {string} S
 * @return {number}
 */
var numJewelsInStones = function (J, S) {
  const jewels = {};
  for (let jewel of J) {
    jewels[jewel] = true;
  }

  let jewelCount = 0;
  for (let stone of S) {
    if (jewels[stone]) {
      jewelCount++;
    }
  }

  return jewelCount;
};

console.log(numJewelsInStones("aA", "aAAbbbb")); // 3
console.log(numJewelsInStones("z", "ZZ")); // 0