petergi

// 17% faster than using filter on set

function difference(a, b) {
    const s = new Set(b)
    const result = []
    for (const x of a) {
        if (!s.has(x)) {
            result.push(x)
        }
    }

petergi

/**
 * Check if a given string is a palindrome.
 *
 * @param {string} str - The string to be checked.
 * @return {boolean} Returns true if the string is a palindrome, false otherwise.
 */
function isPalindrome(str) {
    const formattedStr = str.toLowerCase().replace(/[\W_]/g, "");
    const reversedStr = formattedStr.split("").reverse().join("");
    return formattedStr === reversedStr;

petergi

// This updated version should be more efficient due to the constant-time lookup in the dictionary, the use of StringBuilder for efficient string concatenation, and the iteration over the lookup keys in descending order.
func toRomanNumeral(_ num: Int) -> String {
    let lookup: [Int: String] = [
        1000: "M",
        900: "CM",
        500: "D",
        400: "CD",
        100: "C",
        90: "XC",
        50: "L",

petergi

func isPangram(string: String) -> Bool {
    let alphabet = "abcdefghijklmnopqrstuvwxyz"
    let lowerCaseString = string.lowercased()
    
    for letter in alphabet {
        if !lowerCaseString.contains(letter) {
            return false
        }
    }
    

petergi

/**
 * Checks if a string is a Pangram.
 *
 * @param {string} string - The string to be checked.
 * @return {boolean} Returns true if the string is a pangram, false otherwise.
 */
const isPangram = (string) => {
    const alphabet = "abcdefghijklmnopqrstuvwxyz"
    const lowerCaseString = string.toLowerCase()

petergi

// Removed the localeCompare function call
// Replaced it with a more efficient comparison using the less-than and greater-than operators.
// This avoids the overhead of string comparison and should make the function faster.

/**
 * Sorts an array of objects alphabetically based on a specified getter function.
 *
 * @param {Array} arr - The array to be sorted.
 * @param {Function} getter - The getter function used to retrieve the value to compare.
 * @param {string} [order="asc"] - The order in which to sort the array. Default is "asc" (ascending).

petergi

// - Use the `split()` method to convert the string `str` into an array of characters.
// - Use the `sort()` method with a compare function to sort the characters in the array.
// - Use the `join()` method to recombine the sorted characters into a string.

/**
 * Sorts the characters in a string in ascending order.
 *
 * @param {string} str - The string to sort.
 * @return {string} The sorted string.
 */

petergi

// Instead of using an object with item and index properties, used an array with [item, index] values.
// This reduces the memory footprint and improves performance.
// Modified the .map() and .sort() functions to work with the array of [item, index] pairs.
// Used destructuring assignment in the .map() function to extract only the item value from each pair.

/**
 * Sorts an array in a stable manner using a custom compare function.
 *
 * @param {Array} arr - The array to be sorted.
 * @param {Function} compare - The compare function used to determine the order of elements.

petergi

func weightedAverage(nums: [Double], weights: [Double]) -> Double {
    var sum = 0.0
    var weightSum = 0.0

    for i in 0..<nums.count {
        sum += nums[i] * weights[i]
        weightSum += weights[i]
    }

    return sum / weightSum

petergi

///
///
/// # Arguments
///
/// * `nums`:
/// * `weights`:
///
/// returns: f64
///
/// # Examples