Problem47.js

// Problem 47
//
// This problem was asked by Facebook.
//
// Given a array of numbers representing the stock prices of a company in chronological order,
// write a function that calculates the maximum profit you could have made from buying and selling that stock once.
// You must buy before you can sell it.
//
// For example, given [9, 11, 8, 5, 7, 10], you should return 5,
// since you could buy the stock at 5 dollars and sell it at 10 dollars.
//
// https://leetcode.com/problems/best-time-to-buy-and-sell-stock/description/
//
// O(N) Time complexity
// O(1) Space complexity
// N is the number of elements in the array

function maxProfit(prices) {
  if (prices.length === 0) return 0;
  let min = prices[0];
  let profit = 0;
  for (let i = 1; i < prices.length; i++) {
    const price = prices[i];
    profit = Math.max(profit, price - min);
    min = Math.min(min, price);
  }
  return profit;
}

export default maxProfit;