Practice: Stock Price Calculation

OK grab your journal and dive in with me! I'll be solving this question by hand I urge you to do the same. I'll show you the solution near the end - but give it your best shot!

This question is from InterviewCake - thanks to Parker Phinney for permission to use. You can solve it there right now, if you like, as it’s part of the free questions.

Here’s the question:

Write an efficient function that takes stockPricesYesterday and returns the best profit I could have made from 1 purchase and 1 sale of 1 Apple stock yesterday.

Starter code:

<span class="hljs-comment">//The values are the price in dollars of Apple stock at that time.</span>
<span class="hljs-keyword">var</span> stockPricesYesterday = [<span class="hljs-number">10</span>, <span class="hljs-number">7</span>, <span class="hljs-number">5</span>, <span class="hljs-number">8</span>, <span class="hljs-number">11</span>, <span class="hljs-number">9</span>];

<span class="hljs-title function_">getMaxProfit</span>(stockPricesYesterday);
<span class="hljs-comment">// returns 6 (buying for $5 and selling for $11)</span>