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Mar 11, 2021C S
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graph example

Nov 19, 2022CodeCatch

0 likes • 4 views

class Graph {
constructor(directed = true) {
this.directed = directed;
this.nodes = [];
this.edges = new Map();
}
addNode(key, value = key) {
this.nodes.push({ key, value });
}
addEdge(a, b, weight) {
this.edges.set(JSON.stringify([a, b]), { a, b, weight });
if (!this.directed)
this.edges.set(JSON.stringify([b, a]), { a: b, b: a, weight });
}
removeNode(key) {
this.nodes = this.nodes.filter(n => n.key !== key);
[...this.edges.values()].forEach(({ a, b }) => {
if (a === key || b === key) this.edges.delete(JSON.stringify([a, b]));
});
}
removeEdge(a, b) {
this.edges.delete(JSON.stringify([a, b]));
if (!this.directed) this.edges.delete(JSON.stringify([b, a]));
}
findNode(key) {
return this.nodes.find(x => x.key === key);
}
hasEdge(a, b) {
return this.edges.has(JSON.stringify([a, b]));
}
setEdgeWeight(a, b, weight) {
this.edges.set(JSON.stringify([a, b]), { a, b, weight });
if (!this.directed)
this.edges.set(JSON.stringify([b, a]), { a: b, b: a, weight });
}
getEdgeWeight(a, b) {
return this.edges.get(JSON.stringify([a, b])).weight;
}
adjacent(key) {
return [...this.edges.values()].reduce((acc, { a, b }) => {
if (a === key) acc.push(b);
return acc;
}, []);
}
indegree(key) {
return [...this.edges.values()].reduce((acc, { a, b }) => {
if (b === key) acc++;
return acc;
}, 0);
}
outdegree(key) {
return [...this.edges.values()].reduce((acc, { a, b }) => {
if (a === key) acc++;
return acc;
}, 0);
}
}
const g = new Graph();
g.addNode('a');
g.addNode('b');
g.addNode('c');
g.addNode('d');
g.addEdge('a', 'c');
g.addEdge('b', 'c');
g.addEdge('c', 'b');
g.addEdge('d', 'a');
g.nodes.map(x => x.value); // ['a', 'b', 'c', 'd']
[...g.edges.values()].map(({ a, b }) => `${a} => ${b}`);
// ['a => c', 'b => c', 'c => b', 'd => a']
g.adjacent('c'); // ['b']
g.indegree('c'); // 2
g.outdegree('c'); // 1
g.hasEdge('d', 'a'); // true
g.hasEdge('a', 'd'); // false
g.removeEdge('c', 'b');
[...g.edges.values()].map(({ a, b }) => `${a} => ${b}`);
// ['a => c', 'b => c', 'd => a']
g.removeNode('c');
g.nodes.map(x => x.value); // ['a', 'b', 'd']
[...g.edges.values()].map(({ a, b }) => `${a} => ${b}`);
// ['d => a']
g.setEdgeWeight('d', 'a', 5);
g.getEdgeWeight('d', 'a'); // 5

permutations

Nov 19, 2022CodeCatch

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const permutations = arr => {
if (arr.length <= 2) return arr.length === 2 ? [arr, [arr[1], arr[0]]] : arr;
return arr.reduce(
(acc, item, i) =>
acc.concat(
permutations([...arr.slice(0, i), ...arr.slice(i + 1)]).map(val => [
item,
...val,
])
),
[]
);
};
permutations([1, 33, 5]);
// [ [1, 33, 5], [1, 5, 33], [33, 1, 5], [33, 5, 1], [5, 1, 33], [5, 33, 1] ]

heap sort

Nov 19, 2022CodeCatch

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const heapsort = arr => {
const a = [...arr];
let l = a.length;
const heapify = (a, i) => {
const left = 2 * i + 1;
const right = 2 * i + 2;
let max = i;
if (left < l && a[left] > a[max]) max = left;
if (right < l && a[right] > a[max]) max = right;
if (max !== i) {
[a[max], a[i]] = [a[i], a[max]];
heapify(a, max);
}
};
for (let i = Math.floor(l / 2); i >= 0; i -= 1) heapify(a, i);
for (i = a.length - 1; i > 0; i--) {
[a[0], a[i]] = [a[i], a[0]];
l--;
heapify(a, 0);
}
return a;
};
heapsort([6, 3, 4, 1]); // [1, 3, 4, 6]

Authenticate Discord User

Mar 28, 2023Helper

0 likes • 1 view

const Discord = require('discord.js');
const client = new Discord.Client();
const token = 'YOUR_BOT_TOKEN';
// When the bot is ready, log a message to the console
client.on('ready', () => {
console.log(`Logged in as ${client.user.tag}!`);
});
// When a user sends a message, check if they are authenticated
client.on('message', async (msg) => {
if (!msg.author.bot && !msg.author.authenticated) {
const filter = (m) => m.author.id === msg.author.id;
const collector = msg.channel.createMessageCollector(filter, { time: 15000 });
// Send an authentication message to the user
msg.author.send('Please authenticate yourself by clicking this link: ' + generateAuthURL(msg.author.id));
collector.on('collect', async (m) => {
// Check if the message contains the authentication code
if (m.content.startsWith('!auth ')) {
const code = m.content.slice(6);
const { access_token } = await getAccessToken(code);
// Set the user's authenticated status and access token
msg.author.authenticated = true;
msg.author.access_token = access_token;
collector.stop();
}
});
collector.on('end', () => {
if (!msg.author.authenticated) {
msg.author.send('Authentication timed out.');
}
});
}
});
// Generate an authentication URL for the user
function generateAuthURL(userId) {
const redirectURI = encodeURIComponent('YOUR_REDIRECT_URL');
const scopes = 'identify';
const clientID = 'YOUR_CLIENT_ID';
return `https://discord.com/api/oauth2/authorize?client_id=${clientID}&redirect_uri=${redirectURI}&response_type=code&scope=${scopes}&state=${userId}`;
}
// Exchange the authorization code for an access token
async function getAccessToken(code) {
const redirectURI = encodeURIComponent('YOUR_REDIRECT_URL');
const clientID = 'YOUR_CLIENT_ID';
const clientSecret = 'YOUR_CLIENT_SECRET';
const res = await fetch('https://discord.com/api/oauth2/token', {
method: 'POST',
headers: {
'Content-Type': 'application/x-www-form-urlencoded',
},
body: `grant_type=authorization_code&code=${code}&redirect_uri=${redirectURI}&client_id=${clientID}&client_secret=${clientSecret}`,
});
return await res.json();
}
client.login(token);

Express Login Endpoint

Mar 11, 2021C S

0 likes • 4 views

router.post("/", async (req, res) => {
const { email, password } = req.body;
try {
if (!email) return res.status(400).json({ msg: "An email is required" });
if (!password)
return res.status(400).json({ msg: "A password is required" });
const user = await User.findOne({ email }).select("_id password");
if (!user) return res.status(400).json({ msg: "Invalid credentials" });
const match = await bcrypt.compare(password, user.password);
if (!match) return res.status(400).json({ msg: "Invalid credentials" });
const accessToken = genAccessToken({ id: user._id });
const refreshToken = genRefreshToken({ id: user._id });
res.cookie("token", refreshToken, {
expires: new Date(Date.now() + 604800),
httpOnly: true,
});
res.json({ accessToken });
} catch (err) {
console.log(err.message);
res.status(500).json({ msg: "Error logging in user" });
}
});

hamming distance

Nov 19, 2022CodeCatch

0 likes • 0 views

const hammingDistance = (num1, num2) =>
((num1 ^ num2).toString(2).match(/1/g) || '').length;
hammingDistance(2, 3); // 1