interviewcake-problem-1.js

// https://www.interviewcake.com/question/javascript/stock-price

function getMaxProfit(stockPrices) {
    var lowestPrice = stockPrices[0];
    var maxProfit = stockPrices[1] - lowestPrice;
    
    for (var i = 1; i < stockPrices.length; i++) {
        var difference = stockPrices[i] - lowestPrice;
        
        if (difference > maxProfit) {
            maxProfit = difference;
        }
        
        if (stockPrices[i] < lowestPrice) {
            lowestPrice = stockPrices[i];
        }
    }
    
    return maxProfit;
}

function debug(message) {
    console.log("DEBUG: " + message);
}

var genericPrices = [10, 7, 5, 8, 11, 9];
var negativePrices = [10, 9, 5, 3, 1, 0];

console.log(getMaxProfit(negativePrices));

Currently has an O(n^2) complexity which isn't great...

Now accounts for negative values being the best return on investment.

Now with O(n) complexity and O(1) storage!