4. 寻找两个有序数组的中位数(python3)

 Python3:

class Solution:
    def findMedianSortedArrays(self, nums1, nums2):
        """
        :type nums1: List[int]
        :type nums2: List[int]
        :rtype: float
        """
        A, B = nums1, nums2
        m, n = len(A), len(B)
        if m > n:
            A, B, m, n = B, A, n, m
        if n == 0:
            raise ValueError
            
        imin, imax, half_len = 0, m, (m + n + 1) // 2
        while imin <= imax:
            i = (imin + imax) // 2
            j = half_len - i
            if i < m and B[j-1] > A[i]:
                # i is too small, must increase it
                imin = i + 1
            elif i > 0 and A[i-1] > B[j]:
                # i is too big, must decrease it
                imax = i - 1
            else:
                # i is perfect

                if i == 0: max_of_left = B[j-1]
                elif j == 0: max_of_left = A[i-1]
                else: max_of_left = max(A[i-1], B[j-1])

                if (m + n) % 2 == 1:
                    return max_of_left

                if i == m: min_of_right = B[j]
                elif j == n: min_of_right = A[i]
                else: min_of_right = min(A[i], B[j])

                return (max_of_left + min_of_right) / 2.0