两个有序数组的中位数.py

'''
二分的思想
'''
class Solution:
    def findMedianSortedArrays(self, nums1, nums2):
        """
        :type nums1: List[int]
        :type nums2: List[int]
        :rtype: float
        """
        m, n = len(nums1), len(nums2)
        if m > n:
            nums1, nums2, m, n = nums2, nums1, n, m
        if n == 0:
            raise ValueError

        imin, imax, half_len = 0, m, (m + n + 1) // 2
        while imin <= imax:
            '''
            i,j为
            '''
            i = (imin + imax) // 2
            j = half_len - i
            if i < m and nums2[j-1] > nums1[i]:
                # i is too small, must increase it
                imin = i + 1
            elif i > 0 and nums1[i-1] > nums2[j]:
                # i is too big, must decrease it
                imax = i - 1
            else:
                # i is perfect

                if i == 0: max_of_left = nums2[j-1]
                elif j == 0: max_of_left = nums1[i-1]
                else: max_of_left = max(nums1[i-1], nums2[j-1])

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

                if i == m: min_of_right = nums2[j]
                elif j == n: min_of_right = nums1[i]
                else: min_of_right = min(nums1[i], nums2[j])

                return (max_of_left + min_of_right) / 2.0