Maximum Size of a Set After Removals
<p>You are given two <strong>0-indexed</strong> integer arrays <code>nums1</code> and <code>nums2</code> of even length <code>n</code>.</p>

<p>You must remove <code>n / 2</code> elements from <code>nums1</code> and <code>n / 2</code> elements from <code>nums2</code>. After the removals, you insert the remaining elements of <code>nums1</code> and <code>nums2</code> into a set <code>s</code>.</p>

<p>Return <em>the <strong>maximum</strong> possible size of the set</em> <code>s</code>.</p>

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

<pre>
<strong>Input:</strong> nums1 = [1,2,1,2], nums2 = [1,1,1,1]
<strong>Output:</strong> 2
<strong>Explanation:</strong> We remove two occurences of 1 from nums1 and nums2. After the removals, the arrays become equal to nums1 = [2,2] and nums2 = [1,1]. Therefore, s = {1,2}.
It can be shown that 2 is the maximum possible size of the set s after the removals.
</pre>

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

<pre>
<strong>Input:</strong> nums1 = [1,2,3,4,5,6], nums2 = [2,3,2,3,2,3]
<strong>Output:</strong> 5
<strong>Explanation:</strong> We remove 2, 3, and 6 from nums1, as well as 2 and two occurrences of 3 from nums2. After the removals, the arrays become equal to nums1 = [1,4,5] and nums2 = [2,3,2]. Therefore, s = {1,2,3,4,5}.
It can be shown that 5 is the maximum possible size of the set s after the removals.
</pre>

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

<pre>
<strong>Input:</strong> nums1 = [1,1,2,2,3,3], nums2 = [4,4,5,5,6,6]
<strong>Output:</strong> 6
<strong>Explanation:</strong> We remove 1, 2, and 3 from nums1, as well as 4, 5, and 6 from nums2. After the removals, the arrays become equal to nums1 = [1,2,3] and nums2 = [4,5,6]. Therefore, s = {1,2,3,4,5,6}.
It can be shown that 6 is the maximum possible size of the set s after the removals.
</pre>

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

<ul>
	<li><code>n == nums1.length == nums2.length</code></li>
	<li><code>1 &lt;= n &lt;= 2 * 10<sup>4</sup></code></li>
	<li><code>n</code> is even.</li>
	<li><code>1 &lt;= nums1[i], nums2[i] &lt;= 10<sup>9</sup></code></li>
</ul>
Greedy; Array; Hash Table
function maximumSetSize(nums1: number[], nums2: number[]): number {
    const s1: Set<number> = new Set(nums1);
    const s2: Set<number> = new Set(nums2);
    const n = nums1.length;
    let [a, b, c] = [0, 0, 0];
    for (const x of s1) {
        if (!s2.has(x)) {
            ++a;
        }
    }
    for (const x of s2) {
        if (!s1.has(x)) {
            ++b;
        } else {
            ++c;
        }
    }
    a = Math.min(a, n >> 1);
    b = Math.min(b, n >> 1);
    return Math.min(a + b + c, n);
}
