Hash Table Implementation
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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() {
if (!this.data.length) {
return undefined
}
let result = []
// loop through all the elements
for (let i = 0; i < this.data.length; i++) {
// if it's not an empty memory cell
if (this.data[i] && this.data[i].length) {
// but also loop through all the potential collisions
if (this.data.length > 1) {
for (let j = 0; j < this.data[i].length; j++) {
result.push(this.data[i][j][0])
}
} else {
result.push(this.data[i][0])
}
}
}
return result;
}
}
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()
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