Relocate Marbles
<p>You are given a <strong>0-indexed</strong> integer array <code>nums</code> representing the initial positions of some marbles. You are also given two <strong>0-indexed </strong>integer arrays <code>moveFrom</code> and <code>moveTo</code> of <strong>equal</strong> length.</p>

<p>Throughout <code>moveFrom.length</code> steps, you will change the positions of the marbles. On the <code>i<sup>th</sup></code> step, you will move <strong>all</strong> marbles at position <code>moveFrom[i]</code> to position <code>moveTo[i]</code>.</p>

<p>After completing all the steps, return <em>the sorted list of <strong>occupied</strong> positions</em>.</p>

<p><strong>Notes:</strong></p>

<ul>
	<li>We call a position <strong>occupied</strong> if there is at least one marble in that position.</li>
	<li>There may be multiple marbles in a single position.</li>
</ul>

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

<pre>
<strong>Input:</strong> nums = [1,6,7,8], moveFrom = [1,7,2], moveTo = [2,9,5]
<strong>Output:</strong> [5,6,8,9]
<strong>Explanation:</strong> Initially, the marbles are at positions 1,6,7,8.
At the i = 0th step, we move the marbles at position 1 to position 2. Then, positions 2,6,7,8 are occupied.
At the i = 1st step, we move the marbles at position 7 to position 9. Then, positions 2,6,8,9 are occupied.
At the i = 2nd step, we move the marbles at position 2 to position 5. Then, positions 5,6,8,9 are occupied.
At the end, the final positions containing at least one marbles are [5,6,8,9].</pre>

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

<pre>
<strong>Input:</strong> nums = [1,1,3,3], moveFrom = [1,3], moveTo = [2,2]
<strong>Output:</strong> [2]
<strong>Explanation:</strong> Initially, the marbles are at positions [1,1,3,3].
At the i = 0th step, we move all the marbles at position 1 to position 2. Then, the marbles are at positions [2,2,3,3].
At the i = 1st step, we move all the marbles at position 3 to position 2. Then, the marbles are at positions [2,2,2,2].
Since 2 is the only occupied position, we return [2].
</pre>

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

<ul>
	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
	<li><code>1 &lt;= moveFrom.length &lt;= 10<sup>5</sup></code></li>
	<li><code>moveFrom.length == moveTo.length</code></li>
	<li><code>1 &lt;= nums[i], moveFrom[i], moveTo[i] &lt;= 10<sup>9</sup></code></li>
	<li>The test cases are generated such that there is at least a marble in&nbsp;<code>moveFrom[i]</code>&nbsp;at the moment we want to apply&nbsp;the <code>i<sup>th</sup></code>&nbsp;move.</li>
</ul>
Array; Hash Table; Sorting; Simulation
function relocateMarbles(nums: number[], moveFrom: number[], moveTo: number[]): number[] {
    const pos: Set<number> = new Set(nums);
    for (let i = 0; i < moveFrom.length; i++) {
        pos.delete(moveFrom[i]);
        pos.add(moveTo[i]);
    }
    return [...pos].sort((a, b) => a - b);
}
