Bitwise ORs of Subarrays
<p>Given an integer array <code>arr</code>, return <em>the number of distinct bitwise ORs of all the non-empty subarrays of</em> <code>arr</code>.</p>

<p>The bitwise OR of a subarray is the bitwise OR of each integer in the subarray. The bitwise OR of a subarray of one integer is that integer.</p>

<p>A <strong>subarray</strong> is a contiguous non-empty sequence of elements within an array.</p>

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

<pre>
<strong>Input:</strong> arr = [0]
<strong>Output:</strong> 1
<strong>Explanation:</strong> There is only one possible result: 0.
</pre>

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

<pre>
<strong>Input:</strong> arr = [1,1,2]
<strong>Output:</strong> 3
<strong>Explanation:</strong> The possible subarrays are [1], [1], [2], [1, 1], [1, 2], [1, 1, 2].
These yield the results 1, 1, 2, 1, 3, 3.
There are 3 unique values, so the answer is 3.
</pre>

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

<pre>
<strong>Input:</strong> arr = [1,2,4]
<strong>Output:</strong> 6
<strong>Explanation:</strong> The possible results are 1, 2, 3, 4, 6, and 7.
</pre>

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

<ul>
	<li><code>1 &lt;= arr.length &lt;= 5 * 10<sup>4</sup></code></li>
	<li><code>0 &lt;= arr[i] &lt;= 10<sup>9</sup></code></li>
</ul>
Bit Manipulation; Array; Dynamic Programming
class Solution {
public:
    int subarrayBitwiseORs(vector<int>& arr) {
        unordered_set<int> ans;
        unordered_set<int> s;
        for (int x : arr) {
            unordered_set<int> t;
            for (int y : s) {
                t.insert(x | y);
            }
            t.insert(x);
            ans.insert(t.begin(), t.end());
            s = move(t);
        }
        return ans.size();
    }
};