88. Merge Sorted Array.py

"""
https://leetcode.com/problems/merge-sorted-array/

You are given two integer arrays nums1 and nums2, sorted in non-decreasing order, and two integers m and n,
representing the number of elements in nums1 and nums2 respectively.

Merge nums1 and nums2 into a single array sorted in non-decreasing order.

The final sorted array should not be returned by the function, but instead be stored inside the array nums1.
To accommodate this, nums1 has a length of m + n, where the first m elements denote the elements that should be merged,
and the last n elements are set to 0 and should be ignored. nums2 has a length of n.

Example 1:
    Input: nums1 = [1,2,3,0,0,0], m = 3, nums2 = [2,5,6], n = 3
    Output: [1,2,2,3,5,6]
    Explanation: The arrays we are merging are [1,2,3] and [2,5,6].
    The result of the merge is [1,2,2,3,5,6] with the underlined elements coming from nums1.

Example 2:
    Input: nums1 = [1], m = 1, nums2 = [], n = 0
    Output: [1]
    Explanation: The arrays we are merging are [1] and [].
    The result of the merge is [1].

Example 3:
    Input: nums1 = [0], m = 0, nums2 = [1], n = 1
    Output: [1]
    Explanation: The arrays we are merging are [] and [1].
    The result of the merge is [1].
    Note that because m = 0, there are no elements in nums1. The 0 is only there to ensure the merge result can fit in nums1.

"""
import time


class Solution(object):
    def merge(self, nums1, m, nums2, n):
        while n:
            if m and nums1[m - 1] >= nums2[n - 1]:
                nums1[m + n - 1] = nums1[m - 1]
                m -= 1
            else:
                nums1[m + n - 1] = nums2[n - 1]
                n -= 1
        return nums1


solution = Solution()

assert solution.merge([1, 2, 3, 0, 0, 0], 3, [2, 5, 6], 3) == [1, 2, 2, 3, 5, 6]
assert solution.merge([1], 1, [], 0) == [1]
assert solution.merge([0], 0, [1], 1) == [1]
assert solution.merge([2, 0], 1, [1], 1) == [1, 2]