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The HashTable Class in Javascript
Here is the complete implementation of the HashTable class. This could of course be improved by using more efficient data structures and collision resolution algorithms.
Example
class HashTable {
constructor() {
this.container = [];
// Populate the container with empty arrays
// which can be used to add more elements in
// cases of collisions
for (let i = 0; i < 11; i++) {
this.container.push([]);
}
}
display() {
this.container.forEach((value, index) => {
let chain = value
.map(({ key, value }) => `{ ${key}: ${value} }`)
.join(" --> ");
console.log(`${index}: ${chain}`);
});
}
put(key, value) {
let hashCode = this.hash(key);
for (let i = 0; i < this.container[hashCode].length; i++) {
// Replace the existing value with the given key
// if it already exists
if (this.container[hashCode][i].key === key) {
this.container[hashCode][i].value = value;
return;
}
}
// Push the pair at the end of the array
this.container[hashCode].push(new this.KVPair(key, value));
}
get(key) {
let hashCode = this.hash(key);
for (let i = 0; i < this.container[hashCode].length; i++) {
// Find the element in the chain
if (this.container[hashCode][i].key === key) {
return this.container[hashCode][i];
}
}
return undefined;
}
remove(key) {
let hashCode = this.hash(key);
for (let i = 0; i < this.container[hashCode].length; i++) {
// Find the element in the chain
if (this.container[hashCode][i].key === key) {
this.container[hashCode].splice(i, 1);
return true;
}
}
return false;
}
hash(key) {
return key % 11;
}
forEach(callback) {
// For each chain
this.container.forEach(elem => {
// For each element in each chain call callback on KV pair
elem.forEach(({ key, value }) => callback(key, value));
});
}
static join(table1, table2) {
// Check if both args are HashTables
if (!table1 instanceof HashTable || !table2 instanceof HashTable) {
throw new Error("Illegal Arguments");
}
let combo = new HashTable();
table1.forEach((k, v) => combo.put(k, v));
table2.forEach((k, v) => combo.put(k, v));
return combo;
}
}
HashTable.prototype.KVPair = class {
constructor(key, value) {
this.key = key;
this.value = value;
}
};
Updated on: 15-Jun-2020
96 Views
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