leetcode Median of Two Sorted Arrays

class Solution
{
public:
double findMedianSortedArrays(int A[], int m, int B[], int n) {
int total = m + n;
if (total & 0x1)
return find_kth(A, m, B, n, total / 2 + 1);
else
return (find_kth(A, m, B, n, total / 2)
+ find_kth(A, m, B, n, total / 2 + 1)) / 2.0;
}
private:
static int find_kth(int A[], int m, int B[], int n, int k) {
//always assume that m is equal or smaller than n
if (m > n) return find_kth(B, n, A, m, k);
if (m == 0) return B[k - 1];
if (k == 1) return min(A[0], B[0]);
//divide k into two parts
int ia = min(k / 2, m), ib = k - ia;
if (A[ia - 1] < B[ib - 1])
return find_kth(A + ia, m - ia, B, n, k - ia);
else if (A[ia - 1] > B[ib - 1])
return find_kth(A, m, B + ib, n - ib, k - ib);
else
return A[ia - 1];
}
};

别人写的，比归并排序更有效率一点。