LeetCode 771

Using a hash map or a hash table is very prominent in the world of authentication, encryption, cryptography and much more! Hash tables help us encrypt information or data using key-value pairs.

In this article, it will be a brief overview of how to solve LeetCode 771.

The question is,

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".

My steps include:

1. Create a new hash
2. Initialize a counter equal to 0
3. Set the hash with elements in the Jewels string.
4. Iterate over the Stones string and determine if current iteration is in the Hash. If it is, increment a counter
5. Return the counter

var numJewelsInStones = function(jewels, stones) {
    //step 1
    let hash = new Map()
    //step 2 
    let count = 0 
    //step 3 
    for (let ele of jewels) {
        hash.set(ele, ele)
    }
    //step 4 
    for (let i=0; i < stones.length; i++) {
        if (hash.get(stones[i])) {
            count++
        } 
    }
   //step 5  
   return count
};
    let count = 0 
    for (let ele of jewels) {
        hash.set(ele, ele)
    }
    
    for (let i=0; i < stones.length; i++) {
        if (hash.get(stones[i])) {
            count++
        } 
    }
    return count
};