Merge Sorted Array

LeetCode

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.

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].
1def merge(nums1: List[int], m: int, nums2: List[int], n: int) -> None:
2    # Last index of nums1
3    last = m + n - 1
4    
5    # Merge in reverse order
6    while m > 0 and n > 0:
7        if nums1[m - 1] > nums2[n - 1]:
8            nums1[last] = nums1[m - 1]
9            m -= 1
10        else:
11            nums1[last] = nums2[n - 1]
12            n -= 1
13        last -= 1
14        
15    # Fill remaining from nums2 if any
16    while n > 0:
17        nums1[last] = nums2[n - 1]
18        n, last = n - 1, last - 1
Previous
Interval List Intersections
Next
Parity Sorting
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Step 1 / 5
Step 1:
Initialize pointers m=3 (end of nums1 data), n=3 (end of nums2), last=5.
Pointers: last=5, m=2, n=2
Focus: select @ [2, 5]