HashTables
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class HashTable
{
constructor(size)
{
this.data = new Array(size);
}
//Time complexity
//O(1)
_hash(key)
{
let hash = 0;
for(let i = 0; i < key.length; i++)
{
hash = (hash + key.charCodeAt(i) * i) % this.data.length;
}
return hash;
}
//Time complexity
//O(1)
set(key,value)
{
let address = this._hash(key);
if(!this.data[address])
{
this.data[address] = [];
}
this.data[address].push([key,value]);
return this.data;
}
//Time complexity
//O(1)
//O(n) if there are collisions
get(key)
{
let 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;
}
const keysArray = [];
for(let i = 0; i < this.data.length;i++)
{
if(this.data[i])//if data exists
{
keysArray.push(this.data[i][0][0]);
}
}
return keysArray;
}
}
const myHashTable = new HashTable(100);
myHashTable.set("grapes",5);
myHashTable.set("apples",12);
myHashTable.set("pears",20);
console.log(myHashTable.get("grapes"));
console.log(myHashTable.keys());
JavaScript
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