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6-hash-table.js
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6-hash-table.js
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function HashTable(size) {
this.buckets = Array(size);
this.numBuckets = this.buckets.length;
}
function HashNode(key, value, next) {
this.key = key;
this.value = value;
this.next = next || null
}
HashTable.prototype.hash = function(key) {
let total = 0;
for (let i=0; i< key.length; i++) {
total += key.charCodeAt(i);
}
let bucket = total % this.numBuckets;
return bucket;
}
HashTable.prototype.insert = function(key, value) {
let index = this.hash(key)
console.log('INDEX: ', index)
// if there is not node in bucket then create one
if (!this.buckets[index]) {
this.buckets[index] = new HashNode(key, value);
}
// check first node in bucket and updates its value
else if (this.buckets[index].key === key) {
this.buckets[index].value = value;
}
else {
let currentNode = this.buckets[index];
// goes to the end of the list
while(currentNode.next) {
if (currentNode.next.key === key) {
// updates old node value in bucket with new one
currentNode.next.value = value;
return;
}
currentNode = currentNode.next;
}
// insert node in bucket
currentNode.next = new HashNode(key, value)
}
}
HashTable.prototype.get = function(key) {
let index = this.hash(key);
if (!this.buckets[index]) return null;
else {
let currentNode = this.buckets[index];
while (currentNode) {
if (currentNode.key === key) return currentNode.value;
currentNode = currentNode.next
}
return null;
}
}
HashTable.prototype.retrieveAll = function() {
let allBuckets = [];
for (let i=0; i< this.numBuckets; i++) {
let currentNode = this.buckets[i];
while(currentNode) {
allBuckets.push(currentNode);
currentNode = currentNode.next;
}
}
return allBuckets;
}
module.exports = {
HashTable
}