两个有序数组中，寻找第K大的数

Median of Two Sorted Arrays

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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)).

参考：http://blog.csdn.net/yutianzuijin/article/details/11499917

感谢原作者的整理及分享；

class Solution {
public:
    double findMedianSortedArrays(int A[], int m, int B[], int n) 
    {
        int total = m + n;
if(total & 0x01)
return findKth(A, m, B, n, total/2 + 1);
else
return (findKth(A, m, B, n, total/2) +
      findKth(A, m, B, n, total/2 + 1))/2.0;
    }
    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);
int 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 a[pa-1];
}
};