leedcode 合并两个有序数组

因为nums1里面保证可以放下所有元素，所以从最大的元素开始比较，从nums1的最后面开始放元素。

class Solution(object):
    def merge(self, nums1, m, nums2, n):
        """
        :type nums1: List[int]
        :type m: int
        :type nums2: List[int]
        :type n: int
        :rtype: None Do not return anything, modify nums1 in-place instead.
        """
        count = m + n - 1
        m = m - 1
        n = n - 1
        while m >= 0 and n >= 0:
            if nums1[m] >= nums2[n]:
                nums1[count] = nums1[m]
                count = count - 1
                m = m - 1
            else:
                nums1[count] = nums2[n]
                count = count - 1
                n = n -1
        while m >= 0:
            nums1[count] = nums1[m]
            count = count - 1
            m = m - 1
        while n >= 0:
            nums1[count] = nums2[n]
            count = count - 1
            n = n - 1
        return nums1