4. Median of Two Sorted Arrays    There are two sorted arrays  nums1  and  nums2  of size m and n respectively.   Find the median of the two sorted arrays.   Example 1:  nums1 = [1, 3] nums2 = [2]  The median is 2.0     Example 2:  nums1 = [1, 2] nums2 = [3, 4]  The median is (2 + 3)/2 = 2.5   The idea is to pick up the numbers in nums2 that are smaller than a number in nums1, until we get the median.   Pay attention:  1. consider three cases: odd, even, and null;  2. max of nums1 may smaller than min of nums2;  3. use float() while doing the division.   My code in Python is as follows:   class Solution(object):      def findMedianSortedArrays(self, nums1, nums2):          """          :type nums1: List[int]          :type nums2: List[int]          :rtype: float          """          m = len(nums1)          n = len(nums...