HashTable
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class HashTable {
constructor(size) {
this.data = new Array(size);
}
_hash(key) {
let hash = 0;
for (let i = 0; i < key.length; i++) {
// O(1)
hash = (hash + key.charCodeAt(i) * i) % this.data.length;
}
return hash;
}
set(key, value) {
// this.data[this._hash(key)] = [key,value];
let address = this._hash(key);
if (!this.data[address]) {
this.data[address] = [];
}
this.data[address].push([key, value]);
// console.log(this.data);
}
get(key) {
// return this.data[this._hash(key)];
let address = this._hash(key);
const currentBucket = this.data[address];
if (currentBucket) {
// Only incase of Hash Collisions
for (let i = 0; i < currentBucket.length; i++) {
if (currentBucket[i][0] === key) {
return currentBucket[i][1];
}
}
} // O(1)
return undefined;
}
keys() {
const keysArray = [];
for (let i = 0; i < this.data.length; i++) { //O(n)
if (this.data[i]) {
if (this.data[i].length !== 1) {
// This is worst case : Hash Collisions
for (let j = 0; j < this.data[i].length; j++) { // O(m)
keysArray.push(this.data[i][j][0]);
}
// O(n*m);
} else {
keysArray.push(this.data[i][0][0]); // O(n)
}
}
}
return keysArray;
}
}
const myHashTable = new HashTable(2);
myHashTable.set("grapes", 100000);
myHashTable.set("apples", 54);
myHashTable.set("oranges", 2);
myHashTable.set("mangoes", 23);
// console.log(myHashTable.get("grapes"));
// console.log(myHashTable.get("apples"));
// console.log(myHashTable.get("oranges"));
// console.log(myHashTable.get("mangoes"));
console.log(myHashTable.keys());
JavaScript
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