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LeetCode Contains Duplicate

Sep 13, 2023C S
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More JavaScript Posts

Flatten an array

Nov 19, 2022CodeCatch

0 likes • 3 views

const flat = arr => [].concat.apply([], arr.map(a => Array.isArray(a) ? flat(a) : a));
// Or
const flat = arr => arr.reduce((a, b) => Array.isArray(b) ? [...a, ...flat(b)] : [...a, b], []);
// Or
// See the browser compatibility at https://caniuse.com/#feat=array-flat
const flat = arr => arr.flat();
// Example
flat(['cat', ['lion', 'tiger']]); // ['cat', 'lion', 'tiger']

power set

Nov 19, 2022CodeCatch

0 likes • 2 views

const powerset = arr =>
arr.reduce((a, v) => a.concat(a.map(r => r.concat(v))), [[]]);
powerset([1, 2]); // [[], [1], [2], [1, 2]]

localStorage Cookie Consent

Oct 9, 2023Helper

0 likes • 263 views

import React, { useState, useEffect } from 'react';
import Link from 'next/link';
export default function CookieBanner() {
// Initialize with a default value (false if not previously set in localStorage)
const [cookieConsent, setCookieConsent] = useState(() =>
localStorage.getItem('cookieConsent') === 'true' ? true : false
);
useEffect(() => {
const newCookieConsent = cookieConsent ? 'granted' : 'denied';
window.gtag('consent', 'update', {
analytics_storage: newCookieConsent
});
localStorage.setItem('cookieConsent', String(cookieConsent));
}, [cookieConsent]);
return !cookieConsent && (
<div>
<div>
<p>
We use cookies to enhance the user experience.{' '}
<Link href='/privacy/'>View privacy policy</Link>
</p>
</div>
<div>
<button type="button" onClick={() => setCookieConsent(false)}>Decline</button>
<button type="button" onClick={() => setCookieConsent(true)}>Allow</button>
</div>
</div>
)
}

kNearestNeighbors

Nov 19, 2022CodeCatch

0 likes • 6 views

const kNearestNeighbors = (data, labels, point, k = 3) => {
const kNearest = data
.map((el, i) => ({
dist: Math.hypot(...Object.keys(el).map(key => point[key] - el[key])),
label: labels[i]
}))
.sort((a, b) => a.dist - b.dist)
.slice(0, k);
return kNearest.reduce(
(acc, { label }, i) => {
acc.classCounts[label] =
Object.keys(acc.classCounts).indexOf(label) !== -1
? acc.classCounts[label] + 1
: 1;
if (acc.classCounts[label] > acc.topClassCount) {
acc.topClassCount = acc.classCounts[label];
acc.topClass = label;
}
return acc;
},
{
classCounts: {},
topClass: kNearest[0].label,
topClassCount: 0
}
).topClass;
};
const data = [[0, 0], [0, 1], [1, 3], [2, 0]];
const labels = [0, 1, 1, 0];
kNearestNeighbors(data, labels, [1, 2], 2); // 1
kNearestNeighbors(data, labels, [1, 0], 2); // 0

Redux Slice

Mar 11, 2021C S

1 like • 0 views

import { createSlice } from "@reduxjs/toolkit";
const alert = createSlice({
name: "alert",
initialState: {
msg: "",
status: "",
},
reducers: {
set_alert: (state, action) => {
return {
...state,
msg: action.payload.msg,
status: action.payload.status,
};
},
clear_alert: (state, action) => {
return {
...state,
msg: "",
status: "",
};
},
},
});
export default alert.reducer;
const { set_alert, clear_alert } = alert.actions;
export const setAlert = (msg, status) => dispatch => {
dispatch(set_alert({ msg, status }));
setTimeout(() => dispatch(clear_alert()), 4000);
};
export const clearAlert = () => dispatch => {
dispatch(clear_alert());
};

Tree Traversal

Oct 16, 2023C S

0 likes • 7 views

class TreeNode {
constructor(data, depth) {
this.data = data;
this.children = [];
this.depth = depth;
}
}
function buildNaryTree(hosts) {
const nodeMap = {};
// Step 1: Create a map of nodes using fqdn as the key
hosts.forEach((host) => {
nodeMap[host.fqdn] = new TreeNode(host, 0); // Initialize depth to 0
});
// Step 2: Iterate through the array and add each node to its parent's list of children
hosts.forEach((host) => {
if (host.displayParent) {
if (nodeMap[host.displayParent]) {
const parent = nodeMap[host.displayParent];
const node = nodeMap[host.fqdn];
node.depth = parent.depth + 1; // Update the depth
parent.children.push(node);
} else {
console.error(`Parent with fqdn ${host.displayParent} not found for ${host.fqdn}`);
}
}
});
// Find the root nodes (nodes with no parent)
const rootNodes = hosts.filter((host) => !host.displayParent).map((host) => nodeMap[host.fqdn]);
return rootNodes;
}
function treeToObjects(node) {
const result = [];
function inOrder(node) {
if (!node) {
return;
}
// Visit the current node and add it to the result
result.push(node.data);
// Visit children nodes first
node.children.forEach((child) => {
inOrder(child);
});
}
inOrder(node);
return result;
}
// Usage example
const hosts = [
{
fqdn: 'fqdn_1',
display_name: 'Host 1',
},
{
fqdn: 'fqdn_2',
display_name: 'Host 2',
displayParent: 'fqdn_1',
},
{
fqdn: 'fqdn_3',
display_name: 'Host 3'
},
{
fqdn: 'fqdn_4',
display_name: 'Host 4',
displayParent: 'fqdn_3',
},
{
fqdn: 'fqdn_5',
display_name: 'Host 5',
displayParent: 'fqdn_1',
},
];
const tree = buildNaryTree(hosts);
// Function to convert the tree to an array of objects
function convertTreeToArray(nodes) {
const result = [];
nodes.forEach((node) => {
result.push(...treeToObjects(node));
});
return result;
}
// Convert the tree back to an array of objects
const arrayFromTree = convertTreeToArray(tree);
console.log(arrayFromTree);