LeetCode-4. Median of Two Sorted Arrays

There are two sorted arrays nums1 and nums2 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)).

Example 1:

nums1 = [1, 3]nums2 = [2]The median is 2.0

Example 2:

nums1 = [1, 2]nums2 = [3, 4]The median is (2 + 3)/2 = 2.5

中位数：奇数列取中间的，偶数列取中间两数的均值。

具体参考网上的递归解法。

边界条件：

1.如果A或B为空，直接返回B[K-1]或A[K-1]；

2.如果k=1，返回A[0]、B[0]中的较小值。

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 a[pa-1];    }    double findMedianSortedArrays(int A[], int m, int B[], int n) {    int sum=m+n;       if(sum%2==1) 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;    }};