714. Best Time to Buy and Sell Stock with Transaction Fee (javascript solution)

Description:

You are given an array prices where prices[i] is the price of a given stock on the ith day, and an integer fee representing a transaction fee.

Find the maximum profit you can achieve. You may complete as many transactions as you like, but you need to pay the transaction fee for each transaction.

Note: You may not engage in multiple transactions simultaneously (i.e., you must sell the stock before you buy again).

Solution:

Time Complexity : O(n)
Space Complexity: O(1)

var maxProfit = function(prices, fee) {
        // The max profit we could make
        let profit = 0;
        // Total profit if we bought at the current price
        let hold = -prices[0];
        // Loop through all the days
        for (let i = 1; i < prices.length; i++) {
            // Check if it would be more profitable to hold or sell
            profit = Math.max(profit, hold + prices[i] - fee);
            // Check if it would be more profitable to hold or buy 
            hold = Math.max(hold, profit - prices[i]);
        }
        return profit;
};