Minimum Difference in Sums After Removal of Elements
<p>You are given a <strong>0-indexed</strong> integer array <code>nums</code> consisting of <code>3 * n</code> elements.</p>

<p>You are allowed to remove any <strong>subsequence</strong> of elements of size <strong>exactly</strong> <code>n</code> from <code>nums</code>. The remaining <code>2 * n</code> elements will be divided into two <strong>equal</strong> parts:</p>

<ul>
	<li>The first <code>n</code> elements belonging to the first part and their sum is <code>sum<sub>first</sub></code>.</li>
	<li>The next <code>n</code> elements belonging to the second part and their sum is <code>sum<sub>second</sub></code>.</li>
</ul>

<p>The <strong>difference in sums</strong> of the two parts is denoted as <code>sum<sub>first</sub> - sum<sub>second</sub></code>.</p>

<ul>
	<li>For example, if <code>sum<sub>first</sub> = 3</code> and <code>sum<sub>second</sub> = 2</code>, their difference is <code>1</code>.</li>
	<li>Similarly, if <code>sum<sub>first</sub> = 2</code> and <code>sum<sub>second</sub> = 3</code>, their difference is <code>-1</code>.</li>
</ul>

<p>Return <em>the <strong>minimum difference</strong> possible between the sums of the two parts after the removal of </em><code>n</code><em> elements</em>.</p>

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

<pre>
<strong>Input:</strong> nums = [3,1,2]
<strong>Output:</strong> -1
<strong>Explanation:</strong> Here, nums has 3 elements, so n = 1. 
Thus we have to remove 1 element from nums and divide the array into two equal parts.
- If we remove nums[0] = 3, the array will be [1,2]. The difference in sums of the two parts will be 1 - 2 = -1.
- If we remove nums[1] = 1, the array will be [3,2]. The difference in sums of the two parts will be 3 - 2 = 1.
- If we remove nums[2] = 2, the array will be [3,1]. The difference in sums of the two parts will be 3 - 1 = 2.
The minimum difference between sums of the two parts is min(-1,1,2) = -1. 
</pre>

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

<pre>
<strong>Input:</strong> nums = [7,9,5,8,1,3]
<strong>Output:</strong> 1
<strong>Explanation:</strong> Here n = 2. So we must remove 2 elements and divide the remaining array into two parts containing two elements each.
If we remove nums[2] = 5 and nums[3] = 8, the resultant array will be [7,9,1,3]. The difference in sums will be (7+9) - (1+3) = 12.
To obtain the minimum difference, we should remove nums[1] = 9 and nums[4] = 1. The resultant array becomes [7,5,8,3]. The difference in sums of the two parts is (7+5) - (8+3) = 1.
It can be shown that it is not possible to obtain a difference smaller than 1.
</pre>

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

<ul>
	<li><code>nums.length == 3 * n</code></li>
	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
	<li><code>1 &lt;= nums[i] &lt;= 10<sup>5</sup></code></li>
</ul>
Array; Dynamic Programming; Heap (Priority Queue)
function minimumDifference(nums: number[]): number {
    const m = nums.length;
    const n = Math.floor(m / 3);
    let s = 0;
    const pre: number[] = Array(m + 1);
    const q1 = new MaxPriorityQueue<number>();
    for (let i = 1; i <= n * 2; ++i) {
        const x = nums[i - 1];
        s += x;
        q1.enqueue(x);
        if (q1.size() > n) {
            s -= q1.dequeue();
        }
        pre[i] = s;
    }
    s = 0;
    const suf: number[] = Array(m + 1);
    const q2 = new MinPriorityQueue<number>();
    for (let i = m; i > n; --i) {
        const x = nums[i - 1];
        s += x;
        q2.enqueue(x);
        if (q2.size() > n) {
            s -= q2.dequeue();
        }
        suf[i] = s;
    }
    let ans = Number.MAX_SAFE_INTEGER;
    for (let i = n; i <= n * 2; ++i) {
        ans = Math.min(ans, pre[i] - suf[i + 1]);
    }
    return ans;
}
