leetcode 之Median of Two Sorted Arrays（五）

double findMedianofTwoSortArrays(int A[], int B[], int m, int n)
{
int total = m + n;
//判断序列长度的奇偶，奇数只有一个中间值，偶数有两个中间值，取平均
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;
}

int find_kth(int A[], int m, int B[], int n, int k)
{
//设定m<=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]);

//删除掉一部分数据
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, m - ib, k - ib);
else
return A[ia - 1];
}