<p>Your task is to calculate <code>a<sup>b</sup></code> mod <code>1337</code> where <code>a</code> is a positive integer and <code>b</code> is an extremely large positive integer given in the form of an array.</p> <p> </p> <p><strong>Example 1:</strong></p> <pre> <strong>Input:</strong> a = 2, b = [3] <strong>Output:</strong> 8 </pre> <p><strong>Example 2:</strong></p> <pre> <strong>Input:</strong> a = 2, b = [1,0] <strong>Output:</strong> 1024 </pre> <p><strong>Example 3:</strong></p> <pre> <strong>Input:</strong> a = 1, b = [4,3,3,8,5,2] <strong>Output:</strong> 1 </pre> <p> </p> <p><strong>Constraints:</strong></p> <ul> <li><code>1 <= a <= 2<sup>31</sup> - 1</code></li> <li><code>1 <= b.length <= 2000</code></li> <li><code>0 <= b[i] <= 9</code></li> <li><code>b</code> does not contain leading zeros.</li> </ul>