[leetcode] 4. Median of Two Sorted Arrays

题目：

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

代码：C++

class Solution {
public:
    double findKth(vector<int> nums1, vector<int> nums2, int i, int j, int k){
        if(nums1.size()-i > nums2.size()-j) return findKth(nums2, nums1, j, i, k);
        if(nums1.size()-i == 0) return  nums2[j+k-1];
        if(k == 1) return min(nums1[i], nums2[j]);
        int a = min(int(nums1.size()-i), k/2);
        int b = k-a;
        if(nums1[i+a-1] > nums2[j+b-1])
            return findKth(nums1, nums2, i, j+b, a);
        else
            return findKth(nums1, nums2, i+a, j, b);
    }
    double findMedianSortedArrays(vector<int>& nums1, vector<int>& nums2) {
        int len1 = nums1.size();
        int len2 = nums2.size();
        if((len1 + len2) % 2 == 1){
            return findKth(nums1, nums2, 0, 0, (len1+len2)/2 + 1);
        }
        else{
            return (findKth(nums1, nums2, 0, 0, (len1+len2)/2) +findKth(nums1, nums2, 0, 0, (len1+len2)/2+1))*0.5;
        }
    }
};