Hash Table
Railway Bridge at Argenteuil, 1873, Claude Monet
1. What is Hash Table?
2. Hash Table Implementation
// title: 'HashTable.js'
const hash = function(string, max) {
let hash = 0;
for (let i = 0; i < string.length; i++) {
hash += string.charCodeAt(i);
}
return hash % max;
}
class HashTable {
constructor() {
this.storage = [];
this.storageLimit = 14;
};
print() {
console.log(this.storage)
};
add(key, value) {
let index = hash(key, this.storageLimit);
if (this.storage[index] === undefined) {
this.storage[index] = [
[key, value]
];
} else {
let inserted = false;
for (let i = 0; i < this.storage[index].length; i++) {
if (this.storage[index][i][0] === key) {
this.storage[index][i][1] = value;
inserted = true;
}
}
if (inserted === false) {
this.storage[index].push([key, value]);
}
}
};
remove(key) {
let index = hash(key, this.storageLimit);
if (this.storage[index].length === 1 && this.storage[index][0][0] === key) {
delete this.storage[index];
} else {
for (let i = 0; i < this.storage[index].length; i++) {
if (this.storage[index][i][0] === key) {
delete this.storage[index][i];
}
}
}
};
lookup(key) {
let index = hash(key, this.storageLimit);
if (this.storage[index] === undefined) {
return undefined;
} else {
for (let i = 0; i < this.storage[index].length; i++) {
if (this.storage[index][i][0] === key) {
return this.storage[index][i][1];
}
}
}
};
}
console.log(hash('quincy', 10)) //5
let ht = new HashTable();
ht.add('beau', 'person');
ht.add('fido', 'dog');
ht.add('rex', 'dinosour');
ht.add('tux', 'penguin')
console.log(ht.lookup('tux')) //penguin
ht.print();
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