Median of Two Sorted Arrays
<p>Given two sorted arrays <code>nums1</code> and <code>nums2</code> of size <code>m</code> and <code>n</code> respectively, return <strong>the median</strong> of the two sorted arrays.</p>

<p>The overall run time complexity should be <code>O(log (m+n))</code>.</p>

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

<pre>
<strong>Input:</strong> nums1 = [1,3], nums2 = [2]
<strong>Output:</strong> 2.00000
<strong>Explanation:</strong> merged array = [1,2,3] and median is 2.
</pre>

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

<pre>
<strong>Input:</strong> nums1 = [1,2], nums2 = [3,4]
<strong>Output:</strong> 2.50000
<strong>Explanation:</strong> merged array = [1,2,3,4] and median is (2 + 3) / 2 = 2.5.
</pre>

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

<ul>
	<li><code>nums1.length == m</code></li>
	<li><code>nums2.length == n</code></li>
	<li><code>0 &lt;= m &lt;= 1000</code></li>
	<li><code>0 &lt;= n &lt;= 1000</code></li>
	<li><code>1 &lt;= m + n &lt;= 2000</code></li>
	<li><code>-10<sup>6</sup> &lt;= nums1[i], nums2[i] &lt;= 10<sup>6</sup></code></li>
</ul>
Array; Binary Search; Divide and Conquer
func findMedianSortedArrays(nums1 []int, nums2 []int) float64 {
	m, n := len(nums1), len(nums2)
	var f func(i, j, k int) int
	f = func(i, j, k int) int {
		if i >= m {
			return nums2[j+k-1]
		}
		if j >= n {
			return nums1[i+k-1]
		}
		if k == 1 {
			return min(nums1[i], nums2[j])
		}
		p := k / 2
		x, y := 1<<30, 1<<30
		if ni := i + p - 1; ni < m {
			x = nums1[ni]
		}
		if nj := j + p - 1; nj < n {
			y = nums2[nj]
		}
		if x < y {
			return f(i+p, j, k-p)
		}
		return f(i, j+p, k-p)
	}
	a, b := f(0, 0, (m+n+1)/2), f(0, 0, (m+n+2)/2)
	return float64(a+b) / 2.0
}