<p>There is a biker going on a road trip. The road trip consists of <code>n + 1</code> points at different altitudes. The biker starts his trip on point <code>0</code> with altitude equal <code>0</code>.</p>
<p>You are given an integer array <code>gain</code> of length <code>n</code> where <code>gain[i]</code> is the <strong>net gain in altitude</strong> between points <code>i</code> and <code>i + 1</code> for all (<code>0 <= i < n)</code>. Return <em>the <strong>highest altitude</strong> of a point.</em></p>