Lucky Numbers in a Matrix
<p>Given an <code>m x n</code> matrix of <strong>distinct </strong>numbers, return <em>all <strong>lucky numbers</strong> in the matrix in <strong>any </strong>order</em>.</p>

<p>A <strong>lucky number</strong> is an element of the matrix such that it is the minimum element in its row and maximum in its column.</p>

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

<pre>
<strong>Input:</strong> matrix = [[3,7,8],[9,11,13],[15,16,17]]
<strong>Output:</strong> [15]
<strong>Explanation:</strong> 15 is the only lucky number since it is the minimum in its row and the maximum in its column.
</pre>

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

<pre>
<strong>Input:</strong> matrix = [[1,10,4,2],[9,3,8,7],[15,16,17,12]]
<strong>Output:</strong> [12]
<strong>Explanation:</strong> 12 is the only lucky number since it is the minimum in its row and the maximum in its column.
</pre>

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

<pre>
<strong>Input:</strong> matrix = [[7,8],[1,2]]
<strong>Output:</strong> [7]
<strong>Explanation:</strong> 7 is the only lucky number since it is the minimum in its row and the maximum in its column.
</pre>

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

<ul>
	<li><code>m == mat.length</code></li>
	<li><code>n == mat[i].length</code></li>
	<li><code>1 &lt;= n, m &lt;= 50</code></li>
	<li><code>1 &lt;= matrix[i][j] &lt;= 10<sup>5</sup></code>.</li>
	<li>All elements in the matrix are distinct.</li>
</ul>
Array; Matrix
func luckyNumbers(matrix [][]int) (ans []int) {
	m, n := len(matrix), len(matrix[0])
	rows, cols := make([]int, m), make([]int, n)
	for i := range rows {
		rows[i] = 1 << 30
	}
	for i, row := range matrix {
		for j, x := range row {
			rows[i] = min(rows[i], x)
			cols[j] = max(cols[j], x)
		}
	}
	for i, row := range matrix {
		for j, x := range row {
			if rows[i] == cols[j] {
				ans = append(ans, x)
			}
		}
	}
	return
}