88. Merge Sorted Array

Given two sorted integer arrays nums1 and nums2, merge nums2 into nums1 as one sorted array.

Note:

You may assume that nums1 has enough space (size that is greater or equal to m + n) to hold additional elements from nums2. The number of elements initialized in nums1 and nums2 are m and n respectively.

Solution: Backward Merge

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: void Do not return anything, modify nums1 in-place instead.
        """
        # merge from end to start
        idx = -1
        while n > 0:
            if m > 0 and nums1[m - 1] > nums2[n - 1]:
                nums1[idx] = nums1[m - 1]
                m -= 1
            else:
                nums1[idx] = nums2[n - 1]
                n -= 1
            idx -= 1