[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)).

class Solution {
public:
double findKth(int A[], int m, int B[], int n, int k)
{
//always m<=n
if(m > n)
{
return findKth(B, n, A, m, k);
}

if(m == 0)
{
return B[k -1];
}
if(k == 1)
{
return min(A[0], B[0]);
}
//if A[k/2-1] < B[k/2-1], that means all the elements from A[0] to A[k/2-1]
//(i.e. the k/2 smallest elements in A) are in the range of k smallest elements in the union of A and B.
//Or, in the other word, A[k/2 - 1] can never be larger than the k-th smalleset element in the union of A and B.
int posA = min(m, k/2);
int posB = k - posA;
if(A[posA - 1] < B[posB - 1])
{
return findKth(A + posA, m - posA, B, n, k - posA);
}
else if(A[posA -1] > B[posB - 1])
{
return findKth(A, m, B + posB, n - posB, k - posB);
}
else
{
return A[posA - 1];
}
}

double findMedianSortedArrays(int A[], int m, int B[], int n) {
if((m+n)&0x01)//odd
{
return findKth(A, m, B, n,(m + n)/2 + 1);
}
else //even
{
return (findKth(A, m, B, n, (m + n)/2) + findKth(A, m, B, n, (m + n)/2 + 1))/2;
}

}
};