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)
{
    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]);
    int pa = min(k/2, m), pb =  k - pa;
    if(a[pa - 1] < b[pb - 1])
        return findKth(a+pa, m-pa, b, n, k-pa);
    else if(a[pa - 1] > b[pb - 1])
        return findKth(a, m, b+pb, n-pb, k-pb);
    else
        return b[pb-1];
}
    double findMedianSortedArrays(int A[], int m, int B[], int n) {
        int sum = m + n;
        if(sum & 0x01)
            return findKth(A, m, B, n, sum / 2 + 1);
        else
            return ( findKth(A, m, B, n, sum / 2 ) +
                   findKth(A, m, B, n, sum / 2 + 1) ) / 2;
    }
};