[leetcode] Median of Two Sorted Arrays

There are two sorted arrays A and B of size m and n respectively. Find the median of the two sorted arrays. The overall run time complexity should be O(log (m+n)).
Basic:
Definition of Median:
The median of a finite list of numbers can be found by arranging all the observations from lowest value to highest value and picking the middle one (e.g., the median of {3, 3, 5, 9, 11} is 5). If there is an even number of observations, then there is no single middle value; the median is then usually defined to be the mean of the two middle values (the median of {3, 5, 7, 9} is (5 + 7) / 2 = 6), which corresponds to interpreting the median as the fully trimmed mid-range. 

Algorithm:
This problems seems to be easy, it can be done by O((n+m)log(m+n)) and O((m+n)). However, when it comes to O(log(m+n)), it becomes difficult. We can do this via "find kth largest in a sorted array" and do this separately on odd and even.
1. For odd, just find (m+n)/2 +1 th number. For eve, find (m+n)/2 th and find (m+n)/2+1 th and get the average of these two.
2. For findkth function, we should keep the smaller one as m always and then then it will balanced to be log(m+n).

My Code: