<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>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> a = 2, b = [3]
<strong>Output:</strong> 8
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> a = 2, b = [1,0]
<strong>Output:</strong> 1024
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> a = 1, b = [4,3,3,8,5,2]
<strong>Output:</strong> 1
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= a &lt;= 2<sup>31</sup> - 1</code></li>
	<li><code>1 &lt;= b.length &lt;= 2000</code></li>
	<li><code>0 &lt;= b[i] &lt;= 9</code></li>
	<li><code>b</code> does not contain leading zeros.</li>
</ul>

class Solution:
    def __init__(self,):
        self.pows={}
    def superPow(self, a: int, b: List[int]) -> int:
        tenpow=a**10
        def foo(val,idx):
            if idx==-1: return 1
            else:
                if val not in self.pows: self.pows[val]=(val**10)%1337
                return val**b[idx]*foo(self.pows[val],idx-1)
        return foo(a,len(b)-1)%1337
17300