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Nov 19, 2022CodeCatch
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More JavaScript Posts

linked list

Nov 19, 2022CodeCatch

0 likes • 1 view

class LinkedList {
constructor() {
this.nodes = [];
}
get size() {
return this.nodes.length;
}
get head() {
return this.size ? this.nodes[0] : null;
}
get tail() {
return this.size ? this.nodes[this.size - 1] : null;
}
insertAt(index, value) {
const previousNode = this.nodes[index - 1] || null;
const nextNode = this.nodes[index] || null;
const node = { value, next: nextNode };
if (previousNode) previousNode.next = node;
this.nodes.splice(index, 0, node);
}
insertFirst(value) {
this.insertAt(0, value);
}
insertLast(value) {
this.insertAt(this.size, value);
}
getAt(index) {
return this.nodes[index];
}
removeAt(index) {
const previousNode = this.nodes[index - 1];
const nextNode = this.nodes[index + 1] || null;
if (previousNode) previousNode.next = nextNode;
return this.nodes.splice(index, 1);
}
clear() {
this.nodes = [];
}
reverse() {
this.nodes = this.nodes.reduce(
(acc, { value }) => [{ value, next: acc[0] || null }, ...acc],
[]
);
}
*[Symbol.iterator]() {
yield* this.nodes;
}
}
const list = new LinkedList();
list.insertFirst(1);
list.insertFirst(2);
list.insertFirst(3);
list.insertLast(4);
list.insertAt(3, 5);
list.size; // 5
list.head.value; // 3
list.head.next.value; // 2
list.tail.value; // 4
[...list.map(e => e.value)]; // [3, 2, 1, 5, 4]
list.removeAt(1); // 2
list.getAt(1).value; // 1
list.head.next.value; // 1
[...list.map(e => e.value)]; // [3, 1, 5, 4]
list.reverse();
[...list.map(e => e.value)]; // [4, 5, 1, 3]
list.clear();
list.size; // 0

QM Helper

Mar 22, 2022LeifMessinger

0 likes • 1 view

//QM Helper by Leif Messinger
//Groups numbers by number of bits and shows their binary representations.
//To be used on x.com
const minterms = prompt("Enter your minterms separated by commas").split(",").map(x => parseInt(x.trim()));
const maxNumBits = minterms.reduce(function(a, b) {
return Math.max(a, Math.log2(b));
});
const bitGroups = [];
for(let i = 0; i < maxNumBits; ++i){
bitGroups.push([]);
}
for(const minterm of minterms){
let outputString = (minterm+" ");
//Count the bits
let count = 0;
for (var i = maxNumBits; i >= 0; --i) {
if((minterm >> i) & 1){
++count;
outputString += "1";
}else{
outputString += "0";
}
}
bitGroups[count].push(outputString);
}
document.body.textContent = "";
document.body.style.setProperty("white-space", "pre");
for(const group of bitGroups){
for(const outputString of group){
document.body.textContent += outputString + "\r\n";
}
}

Simple Express Server

Oct 15, 2022CodeCatch

1 like • 233 views

const express = require('express')
const app = express()
const port = 3000
app.get('/', (req, res) => {
res.send('Hello World!')
})
app.listen(port, () => {
console.log(`Example app listening on port ${port}`)
})

arithmetic progression

Nov 19, 2022CodeCatch

0 likes • 2 views

const arithmeticProgression = (n, lim) =>
Array.from({ length: Math.ceil(lim / n) }, (_, i) => (i + 1) * n );
arithmeticProgression(5, 25); // [5, 10, 15, 20, 25]

Timer

Feb 5, 2021LeifMessinger

0 likes • 2 views

class Timer{
start(){
this.startTime = Date.now();
}
stop(){
const dt = Date.now() - this.startTime;
console.log(dt);
return dt;
}
getExecTime(fun, asynchronous){
return asynchronous ? this.getAsyncExecTime(fun) : this.getSyncExecTime(fun);
}
getSyncExecTime(fun){
this.start();
fun();
return this.stop();
}
async getAsyncExecTime(fun){
this.start();
await fun();
return this.stop();
}
static average(fun, numTimes, asynchronous = false){
const times = [];
const promises = [];
let timer = new Timer();
if(asynchronous){
for(let i = 0; i < numTimes; i++){
timer.getAsyncExecTime(fun);
}
}else{
for(let i = 0; i < numTimes; i++){
timer.getSyncExecTime(fun);
}
}
return (times => times.reduce(((sum, acc) => sume + acc), 0) / times.length);
}
static async timeAsync(fun, numTimes){
if(numTimes <= 1) return new Timer().getAsyncExecTime(fun);
const promises = [];
let timer = new Timer(true);
for(let i = 0; i < numTimes; i++){
promises.push(fun().catch((e)=>{}));
}
try{
await Promise.all(promises).catch((e)=>{});
}catch(e){
//do absolutely nothing
}
return timer.stop();
}
constructor(start = false){
if(start) this.start();
}
}

Untitled

Apr 14, 2023Helper

0 likes • 8 views

const quickSort = arr => {
const a = [...arr];
if (a.length < 2) return a;
const pivotIndex = Math.floor(arr.length / 2);
const pivot = a[pivotIndex];
const [lo, hi] = a.reduce(
(acc, val, i) => {
if (val < pivot || (val === pivot && i != pivotIndex)) {
acc[0].push(val);
} else if (val > pivot) {
acc[1].push(val);
}
return acc;
},
[[], []]
);
return [...quickSort(lo), pivot, ...quickSort(hi)];
};
console.log(quickSort([1, 6, 1, 5, 3, 2, 1, 4])) // [1, 1, 1, 2, 3, 4, 5, 6]