Leetcode4-Median of Two Sorted Arrays(Python3)

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

My Solution

class Solution:
    def findMedianSortedArrays(self, nums1, nums2):
        """
        :type nums1: List[int]
        :type nums2: List[int]
        :rtype: float
        """
        nums1.extend(nums2)
        nums1.sort()
        if len(nums1) % 2 == 0:
            return float((nums1[len(nums1)//2-1] + nums1[len(nums1)//2]) / 2)
        else:
            return float(nums1[len(nums1)//2])

Reference (转)

class Solution:
    # @return a float
    def findMedianSortedArrays(self, A, B):
        l=len(A)+len(B)
        return self.findKth(A,B,l//2) if l%2==1 else (self.findKth(A,B,l//2-1)+self.findKth(A,B,l//2))/2.0
            
            
    def findKth(self,A,B,k):
        if len(A)>len(B):
            A,B=B,A
        if not A:
            return B[k]
        if k==len(A)+len(B)-1:
            return max(A[-1],B[-1])
        i=len(A)//2
        j=k-i
        if A[i]>B[j]:
            #Here I assume it is O(1) to get A[:i] and B[j:]. In python, it's not but in cpp it is.
            return self.findKth(A[:i],B[j:],i)
        else:
            return self.findKth(A[i:],B[:j],j)