Prime Number of Set Bits in Binary Representation
<p>Given two integers <code>left</code> and <code>right</code>, return <em>the <strong>count</strong> of numbers in the <strong>inclusive</strong> range </em><code>[left, right]</code><em> having a <strong>prime number of set bits</strong> in their binary representation</em>.</p>

<p>Recall that the <strong>number of set bits</strong> an integer has is the number of <code>1</code>&#39;s present when written in binary.</p>

<ul>
	<li>For example, <code>21</code> written in binary is <code>10101</code>, which has <code>3</code> set bits.</li>
</ul>

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

<pre>
<strong>Input:</strong> left = 6, right = 10
<strong>Output:</strong> 4
<strong>Explanation:</strong>
6  -&gt; 110 (2 set bits, 2 is prime)
7  -&gt; 111 (3 set bits, 3 is prime)
8  -&gt; 1000 (1 set bit, 1 is not prime)
9  -&gt; 1001 (2 set bits, 2 is prime)
10 -&gt; 1010 (2 set bits, 2 is prime)
4 numbers have a prime number of set bits.
</pre>

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

<pre>
<strong>Input:</strong> left = 10, right = 15
<strong>Output:</strong> 5
<strong>Explanation:</strong>
10 -&gt; 1010 (2 set bits, 2 is prime)
11 -&gt; 1011 (3 set bits, 3 is prime)
12 -&gt; 1100 (2 set bits, 2 is prime)
13 -&gt; 1101 (3 set bits, 3 is prime)
14 -&gt; 1110 (3 set bits, 3 is prime)
15 -&gt; 1111 (4 set bits, 4 is not prime)
5 numbers have a prime number of set bits.
</pre>

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

<ul>
	<li><code>1 &lt;= left &lt;= right &lt;= 10<sup>6</sup></code></li>
	<li><code>0 &lt;= right - left &lt;= 10<sup>4</sup></code></li>
</ul>
Bit Manipulation; Math
func countPrimeSetBits(left int, right int) (ans int) {
	primes := map[int]int{}
	for _, v := range []int{2, 3, 5, 7, 11, 13, 17, 19} {
		primes[v] = 1
	}
	for i := left; i <= right; i++ {
		ans += primes[bits.OnesCount(uint(i))]
	}
	return
}