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Apr 14, 2023Helper
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More JavaScript Posts

Get union of arrays

Nov 19, 2022CodeCatch

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const union = (...arr) => [...new Set(arr.flat())];
// Example
union([1, 2], [2, 3], [3]); // [1, 2, 3]

LeetCode Contains Duplicate

Sep 13, 2023C S

0 likes • 2 views

/**
* @param {number[]} nums
* @return {boolean}
*/
var containsDuplicate = function(nums) {
return new Set(nums).size !== nums.length
};

Truncate to fixed decimal

Nov 19, 2022CodeCatch

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const toFixed = (n, fixed) => ~~(Math.pow(10, fixed) * n) / Math.pow(10, fixed);
// Examples
toFixed(25.198726354, 1); // 25.1
toFixed(25.198726354, 2); // 25.19
toFixed(25.198726354, 3); // 25.198
toFixed(25.198726354, 4); // 25.1987
toFixed(25.198726354, 5); // 25.19872
toFixed(25.198726354, 6); // 25.198726

tree traversal

Nov 19, 2022CodeCatch

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class TreeNode {
constructor(key, value = key, parent = null) {
this.key = key;
this.value = value;
this.parent = parent;
this.children = [];
}
get isLeaf() {
return this.children.length === 0;
}
get hasChildren() {
return !this.isLeaf;
}
}
class Tree {
constructor(key, value = key) {
this.root = new TreeNode(key, value);
}
*preOrderTraversal(node = this.root) {
yield node;
if (node.children.length) {
for (let child of node.children) {
yield* this.preOrderTraversal(child);
}
}
}
*postOrderTraversal(node = this.root) {
if (node.children.length) {
for (let child of node.children) {
yield* this.postOrderTraversal(child);
}
}
yield node;
}
insert(parentNodeKey, key, value = key) {
for (let node of this.preOrderTraversal()) {
if (node.key === parentNodeKey) {
node.children.push(new TreeNode(key, value, node));
return true;
}
}
return false;
}
remove(key) {
for (let node of this.preOrderTraversal()) {
const filtered = node.children.filter(c => c.key !== key);
if (filtered.length !== node.children.length) {
node.children = filtered;
return true;
}
}
return false;
}
find(key) {
for (let node of this.preOrderTraversal()) {
if (node.key === key) return node;
}
return undefined;
}
}
const tree = new Tree(1, 'AB');
tree.insert(1, 11, 'AC');
tree.insert(1, 12, 'BC');
tree.insert(12, 121, 'BG');
[...tree.preOrderTraversal()].map(x => x.value);
// ['AB', 'AC', 'BC', 'BCG']
tree.root.value; // 'AB'
tree.root.hasChildren; // true
tree.find(12).isLeaf; // false
tree.find(121).isLeaf; // true
tree.find(121).parent.value; // 'BC'
tree.remove(12);
[...tree.postOrderTraversal()].map(x => x.value);
// ['AC', 'AB']

stripe api json iteration

Nov 18, 2022AustinLeath

0 likes • 1 view

var arr = [{
"success": true,
"data": [
{
"id": "ipi_1KrrbvDOiB2klwsKhuqUWqt1",
"object": "issuing.transaction",
"amount": -2743,
"amount_details": {
"atm_fee": null
},
"authorization": "iauth_1KrrbuDOiB2klwsKoFjQZhhd",
"balance_transaction": "txn_1KrrbwDOiB2klwsK1YkjJJRi",
"card": "ic_1Krqe5DOiB2klwsK44a35eiE",
"cardholder": "ich_1KrqL8DOiB2klwsKtBnZhzYr",
"created": 1650753567,
"currency": "usd",
"dispute": null,
"livemode": false,
"merchant_amount": -2743,
"merchant_currency": "usd",
"merchant_data": {
"category": "advertising_services",
"category_code": "7311",
"city": "San Francisco",
"country": "US",
"name": "Aeros Marketing, LLC",
"network_id": "1234567890",
"postal_code": "94103",
"state": "CA"
},
"metadata": {},
"type": "capture",
"wallet": null
},
{
"id": "ipi_1Krrbvc62B2klwsKhuqUWqt1",
"object": "issuing.transaction",
"amount": -9999,
"amount_details": {
"atm_fee": null
},
"authorization": "iauth_1KrrbuDOiB2klwsKoFjQZhhd",
"balance_transaction": "txn_1KrrbwDOiB2klwsK1YkjJJRi",
"card": "ic_1Krqe5DOiB2klwsK44a35eiE",
"cardholder": "ich_1KrqL8DOiB2klwsKtBnZhzYr",
"created": 1650753567,
"currency": "USD",
"dispute": null,
"livemode": false,
"merchant_amount": -9999,
"merchant_currency": "usd",
"merchant_data": {
"category": "fast_food",
"category_code": "7311",
"city": "San Francisco",
"country": "US",
"name": "Aeros Marketing, LLC",
"network_id": "1234567890",
"postal_code": "94103",
"state": "CA"
},
"metadata": {},
"type": "capture",
"wallet": null
}
]
}];
const reduced = arr.reduce((prev, curr) => {
prev.push({
amount: curr.data[0].merchant_amount,
id: curr.data[0].id,
currency: curr.data[0].currency,
category: curr.data[0].merchant_data.category
});
console.log(prev)
return prev;
}, []);

binary search

Nov 19, 2022CodeCatch

0 likes • 3 views

const binarySearch = (arr, item) => {
let l = 0,
r = arr.length - 1;
while (l <= r) {
const mid = Math.floor((l + r) / 2);
const guess = arr[mid];
if (guess === item) return mid;
if (guess > item) r = mid - 1;
else l = mid + 1;
}
return -1;
};
binarySearch([1, 2, 3, 4, 5], 1); // 0
binarySearch([1, 2, 3, 4, 5], 5); // 4
binarySearch([1, 2, 3, 4, 5], 6); // -1