2288-apply-discount-to-prices.js

/**
 * 2288. Apply Discount to Prices
 * https://leetcode.com/problems/apply-discount-to-prices/
 * Difficulty: Medium
 *
 * A sentence is a string of single-space separated words where each word can contain digits,
 * lowercase letters, and the dollar sign '$'. A word represents a price if it is a sequence
 * of digits preceded by a dollar sign.
 * - For example, "$100", "$23", and "$6" represent prices while "100", "$", and "$1e5" do not.
 *
 * You are given a string sentence representing a sentence and an integer discount. For each
 * word representing a price, apply a discount of discount% on the price and update the word
 * in the sentence. All updated prices should be represented with exactly two decimal places.
 *
 * Return a string representing the modified sentence.
 *
 * Note that all prices will contain at most 10 digits.
 */

/**
 * @param {string} sentence
 * @param {number} discount
 * @return {string}
 */
var discountPrices = function(sentence, discount) {
  const words = sentence.split(' ');
  const discountFactor = 1 - discount / 100;

  for (let i = 0; i < words.length; i++) {
    if (words[i].startsWith('$') && /^[0-9]+$/.test(words[i].slice(1))) {
      const price = parseInt(words[i].slice(1)) * discountFactor;
      words[i] = `$${price.toFixed(2)}`;
    }
  }

  return words.join(' ');
};