Hash_Tables.js

class HashTable {
    constructor(size) {
        this.data = new Array(size);
        // this.data = [];
    }

    _hash(key) {
        let hash = 0;
        for (let i = 0; i < key.length; i++) {
            hash = (hash + key.charCodeAt(i) * i) % this.data.length;
        }
        return hash;
    }

    set(key, value) {
        let address = this._hash(key);
        if (!this.data[address]) {
            this.data[address] = [];
        }
        this.data[address].push([key, value]);
        return this.data;
    }

    get(key) {
        const address = this._hash(key);
        const currentBucket = this.data[address];
        if (currentBucket) {
            for (let i = 0; i < currentBucket.length; i++) {
                if (currentBucket[i][0] === key) {
                    return currentBucket[i][1];
                }
            }
        }
        return undefined;
    }

    keys() {
        const keysArray = [];
        console.log(this.data.length);
        for (let i = 0; i < this.data.length; i++) {
            if (this.data[i]) {
                keysArray.push(this.data[i][0][0]);
            }
        }
        return keysArray;
    }
}

const myHashTable = new HashTable(50);
// myHashTable.set('grapes', 10000)
// myHashTable.set('grapes', 10000)
// myHashTable.get('grapes')
// myHashTable.set('apples', 9)
// myHashTable.get('apples')
// myHashTable.keys()

// const findRecuringVal = (arr) => {
//   for(let i = 0; i < arr.length; i++) {
//     for(let j = i + 1; j < arr.length; j++) {
//       if(arr[i] === arr[j]) {
//         return arr[i];
//       }
//     }
//   }
// };

const findRecuringValHash = (arr) => {
    let map = {};
    for (let i = 0; i < arr.length; i++) {
        if (map[arr[i]] !== undefined) {
            return arr[i];
        } else {
            map[arr[i]] = i;
        }
        console.log("map :::", map);
    }
};

console.log(findRecuringValHash([2, 4, 4, 2, 3, 4, 2, 2]));