88. Merge Sorted Array

---

Description

Easy
Topics
Companies
Hint
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.
 

Constraints:

nums1.length == m + n
nums2.length == n
0 <= m, n <= 200
1 <= m + n <= 200
-109 <= nums1[i], nums2[j] <= 109
 

Follow up: Can you come up with an algorithm that runs in O(m + n) time?

---

Code

package main

import (
	"fmt"
)

func main() {
	merge([]int{1, 2, 3, 0, 0, 0}, 3, []int{2, 5, 6}, 3)
}

func merge(nums1 []int, m int, nums2 []int, n int) {
	// m == 0
	if m == 0 {
		copy(nums1, nums2)
	}

	// n == 0
	if n == 0 {
		return
	}

	// m != 0 && n != 0
	merged := make([]int, m+n)

	k, i, j := 0, 0, 0

	for i < m && j < n {
		if nums1[i] < nums2[j] {
			merged[k] = nums1[i]
			i++
		} else {
			merged[k] = nums2[j]
			j++
		}

		k++
	}

	for i < m {
		merged[k] = nums1[i]
		i++
		k++
	}

	for j < n {
		merged[k] = nums2[j]
		j++
		k++
	}

	copy(nums1, merged)
	fmt.Println(nums1)
}

 

merge 함수는 두 개의 정렬된 배열 nums1과 nums2를 병합하여 하나의 정렬된 배열로 만드는 함수

구현 방식

• nums1은 m + n 크기를 가지며, 앞쪽 m개의 원소는 정렬된 상태이고 뒤쪽 n개의 원소는 0으로 비어 있습니다.
• nums2는 n개의 정렬된 원소를 포함합니다.
• nums1과 nums2를 비교하면서 새로운 배열 merged에 작은 값을 먼저 삽입하고, 남은 요소도 추가합니다.
• 마지막으로 merged 배열을 nums1에 복사하여 병합을 완료