Minimum Area Rectangle
<p>You are given an array of points in the <strong>X-Y</strong> plane <code>points</code> where <code>points[i] = [x<sub>i</sub>, y<sub>i</sub>]</code>.</p>

<p>Return <em>the minimum area of a rectangle formed from these points, with sides parallel to the X and Y axes</em>. If there is not any such rectangle, return <code>0</code>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/solution/0900-0999/0939.Minimum%20Area%20Rectangle/images/rec1.jpg" style="width: 500px; height: 447px;" />
<pre>
<strong>Input:</strong> points = [[1,1],[1,3],[3,1],[3,3],[2,2]]
<strong>Output:</strong> 4
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/solution/0900-0999/0939.Minimum%20Area%20Rectangle/images/rec2.jpg" style="width: 500px; height: 477px;" />
<pre>
<strong>Input:</strong> points = [[1,1],[1,3],[3,1],[3,3],[4,1],[4,3]]
<strong>Output:</strong> 2
</pre>

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

<ul>
	<li><code>1 &lt;= points.length &lt;= 500</code></li>
	<li><code>points[i].length == 2</code></li>
	<li><code>0 &lt;= x<sub>i</sub>, y<sub>i</sub> &lt;= 4 * 10<sup>4</sup></code></li>
	<li>All the given points are <strong>unique</strong>.</li>
</ul>
Geometry; Array; Hash Table; Math; Sorting
func minAreaRect(points [][]int) int {
	d := map[int][]int{}
	xs := []int{}
	for _, p := range points {
		x, y := p[0], p[1]
		d[x] = append(d[x], y)
	}
	for x := range d {
		xs = append(xs, x)
	}
	sort.Ints(xs)
	type pair struct{ x, y int }
	pos := map[pair]int{}
	ans := 1 << 30
	for _, x := range xs {
		ys := d[x]
		sort.Ints(ys)
		for i, y1 := range ys {
			for _, y2 := range ys[i+1:] {
				p := pair{y1, y2}
				if x1, ok := pos[p]; ok {
					ans = min(ans, (x-x1)*(y2-y1))
				}
				pos[p] = x
			}
		}
	}
	if ans == 1<<30 {
		return 0
	}
	return ans
}